Suspended floorboard

ABSTRACT

A materials handling vehicle is provided comprising: a frame; a set of wheels supported on the frame to allow the materials handling vehicle to move across a floor surface; a rider compartment located within the frame for receiving an operator; and an operator support assembly. The operator support assembly comprises a suspended floorboard upon which the operator may stand when located within the rider compartment and an energy absorbing structure coupled to the frame and the suspended floorboard for absorbing and dissipating at least a portion of energy resulting from disturbances encountered by the vehicle as it moves across the floor surface prior to the energy portion reaching the operator standing on the suspended floorboard, the energy absorbing structure including a damping element for effecting a damping function.

This application claims the benefit of U.S. Provisional Application No.60/676,233, filed Apr. 29, 2005 and entitled “Suspended Floorboard,” andU.S. Provisional Application No. 60/706,987, filed Aug. 10, 2005,entitled “Suspended Floorboard,” the disclosures of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a materials handling vehicle, such as alift truck. More particularly, the present invention relates to amaterials handling vehicle having an operator support assembly forabsorbing and dissipating energy resulting from disturbances encounteredby the vehicle during movement across a floor surface so as to isolatethe operator from that energy. While the present invention may beutilized on a variety of materials handling vehicles, it will bedescribed herein with reference to a counterbalanced lift truck forwhich it is particularly applicable and initially being used.

It is known in the prior art to provide a fork lift truck with afloorboard fixedly mounted to a frame of the truck. A rubber mat, uponwhich an operator stands, is provided over the floorboard for absorbinga portion of energy resulting from disturbances encountered by thevehicle during movement across a floor surface.

It is also known in the prior art to provide a fork lift truck with afloorboard supported on a plurality, e.g, four, stiff rubber supports.The floorboard is mounted to the truck frame via the rubber supports.The rubber supports absorb a portion of the energy resulting fromdisturbances encountered by the truck during movement across a floorsurface.

U.S. Pat. No. 5,579,859 discloses a fork lift truck having a floorboardpivotably supported to the vehicle frame. A plurality of compressionsprings are provided beneath the floorboard and function to absorb aportion of energy resulting from disturbances encountered by the vehicleduring movement across a floor surface.

It is desirable to have operator support assemblies for absorbing energyresulting from disturbances encountered by a materials handling vehicleduring movement of the vehicle across a floor surface so as to isolatethe operator from that energy.

BRIEF SUMMARY OF THE INVENTION

In accordance with the present invention, embodiments of an operatorsupport assembly for use in a materials handling vehicle are provided.Each operator support assembly may comprise a suspended floorboard uponwhich an operator stands when located within a rider compartment of thevehicle. An energy absorbing structure is coupled to a frame of thevehicle and the suspended floorboard for absorbing and dissipating atleast a portion of energy resulting from disturbances encountered by thevehicle as it moves across a floor surface. In this way, the energyportion does not reach the operator standing on the suspendedfloorboard.

Standing on a suspended floorboard may include an operator standingfreely on the floorboard without contacting any other surface on thetruck except for gripping a control knob, lever or the like, or standingon the suspended floorboard while contacting a backrest surface, anarmrest, a perch or other supporting surface within an operatorcompartment.

In accordance with a first aspect of the present invention, a materialshandling vehicle comprises a frame and a set of wheels supported on theframe to allow the materials handling vehicle to move across a floorsurface. An operator support assembly is provided comprising a suspendedfloorboard and an energy absorbing structure coupled to the frame andthe suspended floorboard for absorbing and dissipating at least aportion of energy resulting from disturbances encountered by the vehicleas it moves across the floor surface prior to the energy portionreaching the operator standing on the suspended floorboard. The energyabsorbing structure preferably includes a damping element for effectinga damping function.

The operator support assembly may also include one or more of abackrest, an armrest, a control knob or lever such as a multifunctioncontroller or steering tiller or other elements typically found withinan operator's compartment coupled to and suspended with the floorboard.Hence, the backrest, armrest, control knob or lever, or like elementsmay move with the floorboard and an operator standing on the floorboard.

The damping element may comprise at least one damper. The damper may beat least partially filled with a liquid, such as a hydraulic fluid oroil. The energy absorbing structure may further comprise at least onespring for receiving and storing energy.

The energy absorbing structure may further comprise a mast assemblycoupled to the frame and the floorboard for permitting movement of thesuspended floorboard relative to the frame. The mast assembly maycomprise a first element coupled to the frame and a second elementforming a carriage assembly for vertical movement relative to the firstelement. The carriage assembly may include a floorboard support adaptedto receive the floorboard. The first element may comprise a channel suchthat the carriage assembly moves within the channel. The carriageassembly may further comprise front and side load bearings mounted on amain body, with the floorboard support being fixed to the main body formovement with the main body relative to the channel.

The energy absorbing structure may further comprise structure coupledbetween the frame and the at least one spring for varying a preload onthe at least one spring. The structure coupled between the frame and theat least one spring for varying a preload on the at least one spring maycomprise a motor provided with a screw or a lever capable of beingmanually moved by an operator. In accordance with one embodiment, the atleast one spring may be vertically positioned and coupled between thestructure and the floorboard, and the at least one damper may bevertically positioned and coupled between the frame and the floorboard.

In place of the mast assembly, the energy absorbing structure mayfurther comprise a scissors mechanism positioned between the floorboardand a base of the frame. The scissors mechanism may comprise a pair offirst and second scissor arms and a pair of third and fourth scissorarms. The first scissor arm may be pivotably coupled at a first end tothe base of the frame and have a second end in engagement with thefloorboard. The second scissor arm may be pivotably coupled at a firstend to the floorboard and have a second end in engagement with the baseof the frame. The third scissor arm may be pivotably coupled at a firstend to the base of the frame and have a second end in engagement withthe floorboard. The fourth scissor arm may be pivotably coupled at afirst end to the floorboard and have a second end in engagement with thebase of the frame.

The at least one spring may be generally vertically positioned andcoupled between the frame and the scissors mechanism or floorboard, andthe at least one damper may be generally vertically positioned andcoupled between the frame and the scissors mechanism or floorboard.

Alternatively, the at least one spring may be generally horizontallypositioned and coupled between the frame and the scissors mechanism, andthe at least one damper may be generally horizontally positioned andcoupled between the frame and the scissors mechanism.

In accordance with further embodiments of the present invention, thedamping element may comprise a valve. The energy absorbing structure mayfurther comprise a hydraulic piston/cylinder unit coupled to the frame,and a ride accumulator capable of receiving and storing energy. Thevalve may be positioned between the piston/cylinder unit and the rideaccumulator.

The energy absorbing structure may further comprise a mast assemblycoupled to the hydraulic piston/cylinder unit, the frame and thefloorboard for permitting movement of the suspended floorboard relativeto the frame.

In one embodiment, the valve comprises a mechanical valve, such as aneedle valve. The energy absorbing structure may further comprise aprocessor-controlled valve capable of allowing pressurized fluid to passto the hydraulic piston/cylinder unit and the ride accumulator.

In another embodiment, the valve may comprise a firstprocessor-controlled valve. In this embodiment, the energy absorbingstructure may further comprise a second processor-controlled valve, aheight adjust accumulator, a third processor-controlled valve and aprocessor for controlling the first, second and third valves.

The processor may cause the first valve to be in a first position suchthat the first valve is closed when an operator enters or exits a ridercompartment. The processor may move the first valve to a second positionwhen the vehicle is in motion so as to open the first valve to allow thefloorboard to move relative to the frame.

The processor may effect a floorboard height adjustment operation whenthe floorboard is spaced from a neutral position after an operator hasstepped onto the floorboard.

The processor may move the second valve to a closed state when afloorboard height adjustment operation is not being effected. Theprocessor may also move the second valve to an open state so as to allowpressurized air within the ride accumulator to be released when thefloorboard is to be lowered to the neutral position.

The processor may move the third valve to a second position so as toallow pressurized fluid to enter the height adjust accumulator andsubsequently move the second valve to its open state when the floorboardis to be raised to the neutral position.

All embodiments may include upper and lower endstops to confinefloorboard movement between upper and lower stop positions. The endstopsmay be generally elastic in nature and made of natural rubber, urethaneor silicone type materials, and designed with linear or non-linearspring rates and damping characteristics to optimize ride comfort whenthe floorboard is in contact with the endstops.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a perspective view of a fork lift truck including an operatorsupport assembly constructed in accordance with a first embodiment ofthe present invention;

FIG. 2 is a perspective view of the operator support assemblyillustrated in FIG. 1;

FIG. 3 is a perspective view of a mast assembly forming part of theoperator support assembly illustrated in FIG. 2;

FIG. 4 is an exploded view of the mast assembly illustrated in FIG. 3;

FIG. 5 is a perspective view of an operator support assembly constructedin accordance with a second embodiment of the present invention;

FIG. 5A is a view similar to FIG. 5 with the floorboard shown inphantom;

FIG. 6 is a perspective view of an operator support assembly constructedin accordance with a third embodiment of the present invention;

FIG. 7 is a perspective view of an operator support assembly constructedin accordance with a fourth embodiment of the present invention;

FIG. 7A is a perspective view of an adjustable spring and damperassembly forming part of the operator support assembly illustrated inFIG. 7;

FIG. 7B is a top view of the adjustable spring and damper assemblyforming part of the operator support assembly illustrated in FIG. 7;

FIGS. 7C-7F are side views illustrating various angular positions of thefirst and second members of the adjustable spring and damper assemblyillustrated in FIG. 7;

FIG. 8 is a perspective view of an operator support assembly constructedin accordance with a fifth embodiment of the present invention;

FIG. 9 is a schematic view of an operator support assembly constructedin accordance with a sixth embodiment of the present invention;

FIG. 10 is a schematic view of an operator support assembly constructedin accordance with a seventh embodiment of the present invention;

FIG. 11 is a schematic view of an operator support assembly constructedin accordance with a eighth embodiment of the present invention;

FIG. 12 is a perspective view of an operator support assemblyconstructed in accordance with a ninth embodiment of the presentinvention with a lever forming part of a preload adjusting structurepositioned in its lowermost position;

FIG. 13 is a perspective view of the operator support assembly of FIG.12 with the lever positioned in its uppermost position;

FIG. 14 is a perspective view of the operator support assembly of FIG.12 where a carriage assembly is shown spaced from first and second upperstops;

FIG. 15 is a perspective view of the carriage assembly of the operatorsupport assembly of FIG. 12;

FIG. 16 is a perspective view of the operator support assembly of FIG.12 with the carriage assembly removed;

FIG. 17 is a perspective view of the operator support assembly of FIG.12, with a portion of the carriage assembly main body removed;

FIG. 18 is a perspective view of an operator support assemblyconstructed in accordance with a tenth embodiment of the presentinvention where a carriage assembly is shown in an uppermost position;

FIG. 19 is a perspective view of the operator support assembly of FIG.18 where the carriage assembly is shown in an intermediate position;

FIG. 20 is a perspective view of an operator support assembly of FIG. 18where the carriage assembly is shown in a lowermost position;

FIG. 21 is a perspective view of an operator support assembly of FIG. 18where the carriage assembly has been removed and a lever of a preloadadjusting structure is shown engaging a second limit switch; and

FIG. 22 is a perspective view of an operator support assemblyconstructed in accordance with an eleventh embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

Reference is now made to FIG. 1, which is a perspective view of athree-wheel stand-up counterbalanced fork lift truck 10. An operatorsupport assembly 100, constructed in accordance with a first embodimentof the present invention, is incorporated into the truck 10. While thepresent invention is described herein with reference to the stand-upcounterbalanced truck 10, it will be apparent to those skilled in theart that the invention and variations of the invention can be moregenerally applied to a variety of other materials handling vehicles.

The fork lift truck 10 further includes a main body 12 comprising aframe 14, first and second driven wheels coupled to a front portion ofthe frame 14, only the first wheel 16 is illustrated in FIG. 1, and athird steerable wheel 18 coupled to a rear portion of the frame 14. Thefirst, second and third wheels 16 and 18 allow the truck 10 to moveacross a floor surface. The speed and direction of movement (forward orreverse) of the truck 10 can be controlled via a multifunctioncontroller MFC. Steering is effected via a tiller 116A.

A set of forks 20 are coupled to a fork carriage 22, which, in turn, iscoupled to a fork carriage mast assembly 24 for raising/lowering thefork carriage 22 relative to the main body 12. Movement of the forkcarriage 22 is effected using conventional controls.

A rider compartment 30 is located within the main body frame 14 forreceiving an operator. A suspended floorboard 110 forming part of theoperator support assembly 100, see FIGS. 1 and 2, defines a floor in therider compartment 30. When an operator is standing in the ridercompartment 30, a first foot of the operator engages, i.e., pushesdownward on, an operator presence sensor 40. When not depressed, thepresence sensor 40 extends upward through a first opening 110A in thefloorboard 110, see FIG. 2. The sensor 40 must be activated, i.e.,depressed, to permit operation of the truck 10.

A brake pedal 42 extends through a second opening 110B in the floorboard110. To release braking action, the brake pedal 42 is held down by theoperator's second foot. To request braking, the operator removes orreduces a downward force on the brake pedal 42 such that the brake pedal42 moves vertically upward.

Referring again to FIG. 2, the operator support assembly 100 furthercomprises an energy absorbing structure 120 coupled to the truck mainbody frame 14 and the suspended floorboard 110 for absorbing anddissipating at least a portion of energy resulting from disturbancesencountered by the truck 10 as it moves across a floor surface prior tothe energy portion reaching the operator standing on the suspendedfloorboard 110. The disturbances may result from the truck 10 passingover a continuously uneven surface, or moving over large bumps or sharpdrops in the surface. In the embodiment illustrated in FIGS. 1 and 2,the energy absorbing structure 120 comprises a mast assembly 130, firstand second tension springs 140 and 142, a damper 144, and spring preloadadjusting structure 150.

Referring now to FIGS. 3 and 4, the mast assembly 130 includes a firstelement 132, a channel 132A in the illustrated embodiment, which isfixedly coupled, such as by welds, to the frame 14 of the truck mainbody 12. The mast assembly 130 further comprises a second element 134, acarriage assembly 134A in the illustrated embodiment, capable ofvertical movement within the channel 132A. The carriage assembly 134Acomprises a main body 136 having front load bearings 136A and side loadbearings 136B, which allow the main body 136 to move vertically withinthe channel 132A, see FIGS. 3 and 4. The carriage assembly 134A furthercomprises a floorboard support 136C, which is fixedly coupled, such asby welds, to the main body 136 for movement with the main body 136. Thefloorboard support 136C is positioned beneath the floorboard 110 andsupports the floorboard 110 within the rider compartment 30. Thefloorboard support 136C functions as the sole support for the floorboard110; hence, the floorboard 110 is suspended in the rider compartment 30on the support 136C and moves vertically with the floorboard support136C and the main body 136. Preferably, the floorboard 110 is fixedlycoupled to the support 136C.

As illustrated in FIG. 2, the first and second tension springs 140 and142 are weldably coupled at first ends 140A and 142A to the floorboard110 and releasably coupled at second ends 140B and 142B to a movableadjustment bracket 152 forming part of the preload adjusting structure150. It is also contemplated that the spring first ends 140A and 142Amay be releasably coupled to the floorboard 110 such as by extendingthrough openings (not shown) in the floorboard 110.

The damper 144 may comprise a piston rod 144A coupled via a pin 145 to abracket 110C fixedly coupled to the floorboard 110. A cylinder 144B ofthe damper 144 is coupled to a U-shaped bracket 138 via a bolt 138A andcoupling plate 138D. The U-shaped bracket 138 is fixed to the channel132A, which, as noted above, is fixed to the truck main body frame 14.The cylinder 144B may contain a piston/valve assembly (not shown)coupled to the piston rod 144A for movement with the piston rod 144A anda separator piston (not shown) free floating within the cylinder 144B. Afluid such as oil is provided on both sides of the piston/valveassembly, while the separator piston is exposed to the oil on one sideand exposed to a gas, e.g., air, on its other side. In the illustratedembodiment, the damper 144 generates damping action that is differentfor compression and extension. The damper 144 generates the dampingaction by creating a differential pressure across the piston/valveassembly that is proportional to the damping force. The rate of fluidflow through compression and extension orifices in the piston/valveassembly is proportional to the compression and extension velocities.When the piston rod 144A moves inward (compression), which occurs whenthe springs 140, 142 retract for a hole, as discussed below, a quantityof fluid corresponding to the differential volume created is pushedthrough a compression orifice in the piston/valve assembly in a firstdirection to an opposing side of the piston of the piston/valveassembly. When the piston rod 144A moves out (extension), which occurswhen the springs 140, 142 extend for a bump, as discussed below, aquantity of fluid moves through an extension orifice in the piston/valveassembly in a second direction opposite to the first direction to anopposing side of the piston of the piston/valve assembly. Check typevalves are used in the compression and extension orifices to direct thefluid through the appropriate orifice and in the appropriate direction.The compression and extension orifices are different in size to providedifferent damping characteristics in compression and extension. Thedamper 144 may comprise a damper commercially available from Stabilus(Germany) under the product designation Stab-O-Shoc. From mathematicalcalculations, it is believed that the damper 144 should have a lineardamping rate of 4-10 pounds-second/inch for compression, 10-20pounds-second/inch for extension, and a stroke length between about 1inch to about 5 inches and preferably about 2 inches. Other dampingcharacteristics such as variable damping characteristics could be usedto provide other desirable damper responses.

The springs 140 and 142 function to absorb at least a portion of energyresulting from disturbances encountered by the truck 10 as it movesalong a floor surface. The springs 140 and 142 extend (for a bump) andretract (for a hole) in response to receiving kinetic energy and, assuch, store the kinetic energy as potential energy. The damper 144functions to absorb the energy released from the springs 140 and 142 asthe springs 140 and 142 return to an initial position followingextension or retraction, i.e., the damper 144 converts the kineticenergy into heat. The damper 144 further performs a damping function asthe springs 140 and 142 are extended or retracted. By absorbing anddissipating the energy resulting from disturbances encountered by thetruck 10, the springs 140 and 142 and the damper 144 function tosubstantially reduce impact and vibration energy from reaching theoperator standing on the floorboard 110.

A mounting bracket 154, also forming part of the preload adjustingstructure 150, is fixed to the U-shaped bracket 138. The mountingbracket 154 supports a motor 156, which functions to turn a screw 156A.The screw 156A passes through a threaded bore in a back plate 152A ofthe movable bracket 152. By actuating the motor 156 to rotate the screw156A in either a first rotational direction or a second rotationaldirection opposite to the first direction, the movable bracket 152 iscaused to move vertically away from or toward the U-shaped bracket 138.When the bracket 152 moves away from the bracket 138 and toward themotor 156, the first and second springs 140 and 142 are extended, i.e.,lengthened, so as to increase a preload on each spring 140, 142. Whenthe bracket 152 is moved in a direction toward the bracket 138 and awayfrom the motor 156, the preload on the springs 140 and 142 is reduced.

An upper stop 138B is fixedly coupled to the U-shaped bracket 138 so asto limit upward movement of the carriage assembly 134A. One or morelower stops (not shown) are fixed to a lower surface 110D of thefloorboard 110 to limit downward movement of the floorboard 110 relativeto a base (not shown in FIGS. 1 and 2) of the frame 14, i.e., the lowerstops engage the base of the truck main body frame 14 to prevent furtherdownward movement of the floorboard 10 and the carriage assembly 134A.The upper and lower stops are generally elastic in nature and designedto minimize shock transmission while the floorboard 110 is in contactwith the stops. The upper and lower stops may be made of natural rubber,urethane, silicone or other like elastomeric type material. The stops ina preferred embodiment provide a force deflection characteristic, i.e.,they deflect by x amount when a force F is applied against the stop, asdescribed by the following polynomial equation:F=−27.88x ³+251x ²+86.7x

wherein F=force, and x=deflection.

Preferably, the position of the floorboard 110 is located in a neutralposition between an upper stop position where the carriage assembly 134Aengages the upper stop 138B and a lower stop position where the lowerstops on the floorboard 110 engage the base of the frame 14. In theillustrated embodiment, the “neutral position” is equal to a predefinedposition falling within a range equal to ±15% of a centered position.That is, the neutral position is a predefined position which maycomprise a midway position between the upper and lower stop positions ormay be defined by another position falling within the range of ±15% ofthe midway or centered position. The maximum distance that thefloorboard 110 moves between its upper and lower stop positions may befrom about 1 inch to about 5 inches and preferably is about 2 inches.

When a light-weight operator is positioned on the floorboard 110, thefloorboard 110 may be spaced from the neutral position toward the upperstop 138B. Conversely, when a heavy-weight operator is positioned on thefloorboard 110, the floorboard 110 may be spaced from the neutralposition toward the base of the frame 14. So as to allow the floorboard110 to be located at the neutral position subsequent to an operatorstepping onto the floorboard 110, the motor 156 is driven to cause thescrew 156A to rotate in an appropriate direction to vary the preload onthe springs 140 and 142 such that the floorboard 110 is repositioned toits neutral position.

It is contemplated that switches (not shown) or other position sensingtype devices may be provided to sense during a floorboard heightadjustment operation when the floorboard 110 is away from its neutralposition such that appropriate signals are generated by the switches toa processor which causes the motor 156 to drive the screw 156A in anappropriate direction to effect movement of the floorboard 110 to itsneutral position. It is contemplated that the processor may effect afloorboard height adjustment operation so as to move the floorboard toits neutral position just after an operator enters the operator'scompartment 30 and activates the presence sensor 40. Alternatively, anoperator may manually actuate one or more switches (not shown) to drivethe motor 156 in an appropriate direction so as to cause the floorboard110 to be moved to a neutral position, which position may be indicatedvisually to the operator when the floorboard 110 is aligned with analignment mark (not shown) provided on a wall of the frame 14. It isbelieved that the floorboard 110 may accommodate an operator having aweight that falls within a substantially broad range, e.g., from about100 pounds to about 300 pounds, and yet still be located in the neutralposition by varying the preload on the springs 140 and 142.

It is preferred that the operator support assembly 100 have a naturalfrequency between about 1.5 and about 2.5 Hz. It is further preferredthat the floorboard 110 typically move only within a range of positionswell within its upper and lower stop positions during normal operationof the truck 10. It is believed that the energy absorbing structure 120coupled to the floorboard 110 supporting an operator having a weightbetween about 100 pounds and 300 pounds and capable of achieving thesetwo objectives may comprise first and second springs 240 and 242 havinga relaxed length (prior to being coupled to the floorboard 110 and themovable adjustment bracket 152) of from about 6 inches to about 12inches, and a spring rate of from about 25 pounds/inch to about 200pounds/inch.

It is noted that the energy absorbing structure 120 is small in size soas to allow the structure 120 to be easily housed or located behind arider compartment interior wall 14A of the main body frame 14, see FIG.1, where the wall 14A is broken away to allow the structure 120 to beseen. Similarly, the floorboard support 136C is relatively small in sizeso as to allow it to be easily positioned between the floorboard 110 andthe base of the frame 14.

It is believed that the operator support assembly 100 is advantageous asit minimizes shock and vibration transmission to an operator; reducesvehicle ride harshness; allows for significant operator weight range,e.g., 100 pounds to 300 pounds; provides an acceptable ride quality,i.e., softness, during vehicle operation; maintains an acceptablefirmness when an operator enters and exits the vehicle; and may bemanufactured at an acceptable cost.

An operator support assembly 200 constructed in accordance with a secondembodiment of the present invention is illustrated in FIGS. 5 and 5A,where like reference numerals indicate like elements. The operatorsupport assembly 200 may be incorporated into a truck similar to the oneillustrated in FIG. 1 or other materials handling vehicles. The operatorsupport assembly 200 comprises a suspended floorboard 110 and an energyabsorbing structure 220 coupled to the truck main body frame 14 and thesuspended floorboard 110 for absorbing and dissipating at least aportion of the energy resulting from disturbances encountered by thetruck as it moves across a floor surface prior to the energy portionreaching the operator standing on the suspended floorboard 110. Theenergy absorbing structure 220 comprises a scissors mechanism 230, firstand second tension springs 240 and 242, and a damper 244. In thisembodiment, the first and second tension springs 240 and 242 and thedamper 244 are generally vertically positioned and coupled between thetruck main body frame 14 and the floorboard 110. As the floorboard 110is coupled to the scissors mechanism 230, as discussed below, the firstand second tension springs 240 and 242 and the damper 244 mayalternatively be coupled between the truck main body frame 14 and thescissors mechanism 230. It is also contemplated that only a singletension spring may be used instead of the first and second springs 240and 242.

The scissors mechanism 230 comprises a pair of first and second scissorarms 232 and 234 and a pair of third and fourth scissor arms 236 and238. The first scissor arm 232 is pivotably coupled at a first end 232Ato a base 14B of the frame 14 via a block 232D and has a second end 232Bprovided with a roller 232C which moves back and forth along a firsttrack 110E fixedly coupled to the bottom surface 110D of the floorboard110. The second scissor arm 234 is pivotably coupled at a first end 234Ato the floorboard 110 via a block 234D and has a second end 234Bprovided with a roller 234C in movable engagement with the base 14B ofthe frame 14. The third scissor arm 236 is pivotably coupled at a firstend 236A to the base 14B of the frame 14 via a block 236D and has asecond end 236B provided with a roller 236C which moves back and forthalong a second track 110F fixedly coupled to the bottom surface 110D ofthe floorboard 100. The fourth scissor arm 238 is pivotably coupled at afirst end 238A to the floorboard 110 via a block 238D and has a secondend 238B provided with a roller 238C in movable engagement with the base14B of the frame 14.

As illustrated in FIGS. 5 and 5A, the first and second tension springs240 and 242 are coupled at first ends 240A and 242A to the floorboard110 and coupled at second ends 240B and 242B to the truck main bodyframe 14 via bolts 240C and 242C. The damper 244 may comprise a dampercommercially available from Stabilus (Germany) under the productdesignation Stab-O-Shoc. From mathematical calculations, it is believedthat the damper 244 should have having a linear damping rate of 4-10pounds-second/inch for compression, 10-20 pounds-second/inch forextension, and a stroke length between about 1 inch to about 5 inchesand preferably about 2 inches. The damper 244 comprises a piston rod244A coupled via a pin 245 to a bracket 210C fixedly coupled to thefloorboard 110. A cylinder 244B of the damper 244 is coupled to theframe 14 via a bolt 244C.

The scissors mechanism 230 is positioned beneath the floorboard 110 andsupports the floorboard 110 within the truck rider compartment 30, seeFIG. 5. The scissors mechanism 230 functions as the sole support for thefloorboard 110; hence, the floorboard 110 is suspended in the ridercompartment 30 on the scissors mechanism 230. Due to the pivotablerelationship of the first and second arms 232 and 234 and the pivotablerelationship of the third and fourth arms 236 and 238 and because therollers 234C and 238C are capable of moving along the base 14B of theframe 14 and the rollers 232C and 236C are capable of moving along thetracks 110E and 110F, the scissors mechanism 230 moves upward anddownward in the vertical direction, indicated by arrow 202 in FIG. 5, asthe truck encounters disturbances during movement along a floor surface.The floorboard 110 moves with the scissors mechanism 230. The springs240 and 242 function to absorb at least a portion of energy resultingfrom the disturbances encountered by the truck as it moves along a floorsurface. The springs 240 and 242 extend or retract in response toreceiving kinetic energy and as such store the kinetic energy aspotential energy. The damper 244 functions to absorb the energy releasedfrom the springs 240 and 242 as the springs 240 and 242 return to aninitial position following extension or retraction, i.e., the damper 244converts the energy stored in the springs 240 and 242 into heat. Thedamper 244 further performs a damping function as the springs 240 and242 are extended or retracted. By absorbing and dissipating the energyresulting from disturbances encountered by the truck, the springs 240and 242 and damper 244 function to substantially reduce impact andvibration energy from reaching the operator standing on the floorboard110.

An operator support assembly 300 constructed in accordance with a thirdembodiment of the present invention is illustrated in FIG. 6, where likereference numerals indicate like elements. The operator support assembly300 may be incorporated into a truck similar to the one illustrated inFIG. 1 or other materials handling vehicles. The operator supportassembly 300 comprises a suspended floorboard 110 and an energyabsorbing structure 320 coupled to the base 14B of the truck main bodyframe 14 and the suspended floorboard 110 for absorbing and dissipatingat least a portion of energy resulting from disturbances encountered bythe truck as it moves across a floor surface prior to the energy portionreaching the operator standing on the suspended floorboard 110. Theenergy absorbing structure 320 comprises a scissors mechanism 230, firstand second tension springs 340 and 342, and a damper 344. The scissorsmechanism 230 is constructed in the same manner as the one illustratedin FIGS. 5 and 5A. In this embodiment, however, the first and secondtension springs 340 and 342 and the damper 344 are generallyhorizontally positioned and coupled between the truck main body frame 14and the scissors mechanism 230. It is also contemplated that only asingle tension spring may be used instead of the first and secondsprings 340 and 342.

The first and second tension springs 340 and 342 are coupled at firstends 340A and 342A to the scissors mechanism 230 via a cross bar 231 andcoupled at second ends 340B and 342B to the truck main body frame base14B via a cross bar 14C. The damper 344 may comprise a dampercommercially available from Stabilus (Germany) company under the productdesignation Stab-O-Shoc. From mathematical calculations, it is believedthat the damper 344 should have a linear damping rate of 4-10pounds-second/inch for compression, 10-20 pounds-second/inch forextension, and a stroke length between about 1 inch to about 5 inchesand preferably about 2 inches. The damper 344 may comprise a piston rod344A coupled to the cross bar 231. A cylinder 344B of the damper 344 iscoupled to the frame base 14B via the cross bar 14C.

The springs 340 and 342 function to absorb at least a portion of energytransferred to the floorboard 110 resulting from the disturbancesencountered by the truck 10 in which the operator support assembly 300is incorporated. The springs 340 and 342 receive the energy resulting inthe extension or retraction of the springs 340 and 342. By extending orretracting, the springs 340 and 342 store potential energy. The damper344 functions to absorb the energy released from the springs 340 and 342as the springs 340 and 342 return to an initial position following beingextended or retracted, i.e., the damper 344 converts the energy from thesprings 340 and 342 into heat. The damper 344 further performs a dampingfunction as the springs 340 and 342 are extended or retracted. Byabsorbing and dissipating the energy resulting from disturbancesencountered by the truck, the springs 340 and 342 and damper 344function to substantially reduce impact and vibration energy fromreaching the operator standing on the floorboard 110.

An operator support assembly 400 constructed in accordance with a fourthembodiment of the present invention is illustrated in FIGS. 7 and 7A-7F,where like reference numerals indicate like elements. The operatorsupport assembly 400 may be incorporated into a truck similar to the oneillustrated in FIG. 1 or other materials handling vehicles. The operatorsupport assembly 400 comprises a suspended floorboard 110 and an energyabsorbing structure 420 coupled to the truck main body frame 14 and thesuspended floorboard 110 for absorbing and dissipating at least aportion of energy resulting from disturbances encountered by the truckas it moves across a floor surface prior to the energy portion reachingthe operator standing on the suspended floorboard 110. The energyabsorbing structure 420 comprises a scissors mechanism 230, and anadjustable spring and damper assembly 430. The scissors mechanism 230 isconstructed in the same manner as the one illustrated in FIGS. 5 and 5A.

The adjustable spring and damper assembly 430 comprises a first member432 pivotable about a first pivot point 434 defined by a bolt/nutcombination 434A coupling the first member 432 to an extending member14C of the truck main body frame 14, and a second member 436 pivotableabout a second pivot point 438 defined by a bolt/nut combination 438Acoupling the second member 436 to a side wall 14D of the truck main bodyframe 14, see FIGS. 7, 7A and 7B. The first pivot point 434 is spacedfrom the second pivot point 438, as best seen in FIGS. 7C-7F. A pin 432Pextends outwardly from the first member 432 and is coupled to a crossmember 230A of the scissors mechanism 230 such that upward and downwardmovement of the scissors mechanism 230 is transferred to the firstmember 432 causing rotation of the first member 432 about the firstpivot point 434.

A spring 440 and a damper 444 extend between and are coupled to thefirst and second members 432 and 436, see FIGS. 7A and 7B. A first end440A of the spring 440 is coupled to a bolt 432A extending from thefirst member 432. A second end 440B of the spring 440 is coupled to abolt 436A extending from the second member 436. A piston rod 444A of thedamper 444 is coupled to an extension 432B of the first member 432. Acylinder 444B of the damper 444 is coupled to a bolt 436B extending fromthe second member 436.

The scissors mechanism 230 is positioned beneath the floorboard 110 andsupports the floorboard 110 within the truck rider compartment 30, seeFIG. 7. The scissors mechanism 230 functions as the sole support for thefloorboard 110; hence, the floorboard 110 is suspended in the ridercompartment 30 on the scissors mechanism 230. The floorboard 110 moveswith the scissors mechanism 230. As noted above, the pin 432P extendsfrom the first member 432 and is fixedly coupled to the cross member230A of the scissors mechanism 230. Hence, movement of the scissorsmechanism 230 and the floorboard 110 is transferred to the first member432.

The spring 440 functions to absorb at least a portion of energyresulting from the disturbances encountered by the truck 10 as it movesacross a floor surface. The spring 440 extends and retracts resulting init storing energy. The damper 444 functions to absorb the energyreleased from the spring 440 as the spring 440 retracts or extends,i.e., the damper 444 converts the energy stored in the spring 440 intoheat. The damper 444 further performs a damping function as the spring440 is extended or retracted. By absorbing and dissipating the energyresulting from disturbances encountered by the truck 10, the spring 440and damper 444 function to substantially reduce impact and vibrationenergy from reaching the operator standing on the floorboard 110.

The second member 436 includes a lever portion 436C, which may begripped by an operator. The second member 436 further includes aprotrusion (not shown) which is adapted to be received in one of aplurality of recesses 14E formed in the side wall 14D of the truck mainbody frame 14 so as to retain the second member 436 in a desiredposition. By gripping the lever portion 436C, an operator may rotate thesecond member 436 about the second pivot point 438 to change itsposition relative to the side wall 14D, see FIGS. 7C and 7F. By changingthe angular position of the second member 436, the preload on the spring440 as well as its angular position relative to the side wall 14D may bevaried. By rotating the second member 436 counter-clockwise, as viewedin FIGS. 7C and 7F, the length of the spring 440 is increased slightlysuch that the preload on the spring 440 is increased. By increasing thepreload on the spring 440, the magnitude of a force F applied by thespring 440 to the first member 432 increases, see FIG. 7C. Further, thespring 440 becomes more vertically oriented with the counter-clockwiserotation of the second member 436, compare FIG. 7C with FIG. 7F. Theforce F applied by the spring 440 to the first member 432 can beresolved into two components, F_(X) and F_(Y), see FIG. 7C. When thespring 440 is more vertically oriented, the magnitude of its forcecomponent F_(Y) increases. Consequently, when rotating the second member436 counter-clockwise, the force applied by the spring 440 in the Ydirection to the scissors mechanism 230 and, hence, the floorboard 110,increases. Conversely, when rotating the second member 436 clockwise,the force applied by the spring 440 in the Y direction to the scissorsmechanism 230 and, hence, the floorboard 110, decreases.

An upper stop 414A is fixedly coupled to the side wall 14D of the truckmain body frame 14 so as to limit upward movement of the floorboard 110,see FIG. 7. One or more lower stops (not shown) are fixed to a lowersurface 110D of the floorboard 110 to limit downward movement of thefloorboard 110 relative to the base 14B of the frame 14, i.e., the lowerstops engage the base 14B to prevent further downward movement of thefloorboard 110. The upper and lower stops may be made of natural rubber,urethane, silicone or other like elastomeric type material. The stops ina preferred embodiment provide a force deflection characteristic, i.e.,they deflect by x amount when a force F is applied against the stop, asdescribed by the following polynomial equation:F=−27.88x ³+251x ²+86.7x

wherein F=force, and x=deflection.

Preferably, the position of the floorboard 110 is located in a neutralposition between an upper stop position, where the floorboard 110engages the upper stop 414A and a lower stop position, where the lowerstops on the floorboard 110 engage the base of the frame 14. In theillustrated embodiment, the “neutral position” is equal to a predefinedposition falling within a range equal to ±15% of a centered position.The first member 432 of the adjustable spring and damper assembly 430 ispositioned as shown in FIG. 7C when the floorboard 110 is positioned inits upper stop position, the first member 432 is positioned as shown inFIG. 7E when the floorboard 110 is positioned in its lower stop positionand the first member 432 is positioned as shown in FIG. 7D when thefloorboard 110 is positioned in its neutral position. The maximumdistance that the floorboard 110 moves between its upper and lower stoppositions may be from about 1 inch to about 5 inches and preferably isabout 2 inches.

When a light-weight operator is positioned on the floorboard 110, thefloorboard 110 may be spaced from the neutral position toward the upperstop 414A. Conversely, when a heavy-weight operator is positioned on thefloorboard 110, the floorboard 110 may be spaced from the neutralposition toward the base 14B of the frame 14. So as to allow thefloorboard 110 to be located in its neutral position subsequent to anoperator stepping onto the floorboard 110, an operator grips the leverportion 436C and rotates the second member 436 in an appropriatedirection so as to change the preload on the spring 440 as well as itsangular orientation such that the floorboard 110 is repositioned to itsneutral position. A mark (not shown) may be provided on a wall of theframe which, when aligned with the floorboard 110, indicates to theoperator that the floorboard 110 has been moved to its neutral position.It is believed that the floorboard 110 may accommodate an operatorhaving a weight that falls within a substantially broad range, e.g.,from about 100 pounds to about 300 pounds, and yet still be moved to itsneutral position by varying the preload on and angular position of thespring 440.

It is preferred that the operator support assembly 400 have a naturalfrequency between about 1.5 to about 2.5 Hz. It is further preferredthat the floorboard 110 typically move only within a range of positionswell within its upper and lower stop positions during normal operationof the truck 10. It is believed that an energy absorbing structure 420coupled to a floorboard 100 supporting an operator having a weightbetween about 100 pounds and 300 pounds and capable of achieving thesetwo objections may include a spring 440 having a relaxed length (priorto being coupled to the first and second members 432 and 436) of fromabout 6 inches to about 10 inches, and a spring rate of from about 50pounds/inch to about 200 pounds/inch.

It is noted that the energy absorbing structure 420 is small in size soas to allow the structure 420 to be easily housed or located behind arider compartment interior wall of the main body frame 14.

It is believed that the operator support assembly 400 is advantageous asit minimizes shock and vibration transmission to an operator; reducesvehicle ride harshness; allows for significant operator weight range,e.g., 100 pounds to 300 pounds; provides an acceptable ride quality,i.e., softness, during vehicle operation; maintains an acceptablefirmness when an operator enters and exits the vehicle; and may bemanufactured at an acceptable cost.

An operator support assembly 500 constructed in accordance with a fifthembodiment of the present invention is illustrated in FIG. 8, where likereference numerals indicate like elements. The operator support assembly500 may be incorporated into a truck similar to the one illustrated inFIG. 1 or other materials handling vehicles. The operator supportassembly 500 comprises a suspended floorboard 110 and an energyabsorbing structure 520 coupled to the truck main body frame 14 and thesuspended floorboard 110 for absorbing and dissipating at least aportion of energy resulting from disturbances encountered by the truckas it moves across a floor surface prior to the energy portion reachingthe operator standing on the suspended floorboard 110. The energyabsorbing structure 520 comprises a mast assembly 130 and an adjustablespring and damper assembly 530.

The mast assembly 130 is constructed in the same manner as the oneillustrated in FIGS. 2-4. It comprises a channel 132A fixedly coupled tothe frame 14 of the truck main body 12, and a carriage assembly 134Acapable of vertical movement within the channel 132A. The carriageassembly 134A comprises a main body 136 and a floorboard support 136C.

The adjustable spring and damper assembly 530 comprises a first member532 pivotable about a first pivot point 534 defined by a pin 534Acoupling the first member 532 to a wall 14D of the truck main body frame14, and a second member 536 pivotable about a second pivot point 538defined by a pin 538A coupling the second member 536 to the wall 14D ofthe truck main body frame 14. The first pivot point 534 is spaced fromthe second pivot point 538. A cable 532A extends from the first member532 and is fixedly coupled to the carriage assembly 134A such thatupward and downward movement of the carriage assembly 134A istransferred to the first member 532.

An extension spring 540 extends between and is coupled to the first andsecond members 532 and 536, while a damper 544 extends between and iscoupled to the first member 532 and the wall 14D. A first end 540A ofthe spring 540 is coupled to a bolt 532A extending from the first member532. A second end 540B of the spring 540 is coupled to a bolt 536Aextending from the second member 536. A piston rod 544A of the damper544 is coupled to the first member 532. A cylinder 544B of the damper544 is coupled to a bolt/block combination 14F extending from the wall14D.

The floorboard support 136C is positioned beneath the floorboard 110 andsupports the floorboard 110 within the truck rider compartment. Thecarriage assembly 134A functions as the sole support for the floorboard110; hence, the floorboard 110 is suspended in the rider compartment onthe carriage assembly 134A. The floorboard 110 moves with the carriageassembly 134A. As noted above, the cable 532A extends from the firstmember 532 and is fixedly coupled to the carriage assembly 134A. Hence,movement of the carriage assembly 134A and the floorboard 110 istransferred to the first member 532.

The spring 540 functions to absorb at least a portion of energyresulting from the disturbances encountered by the truck 10 as it movesalong a floor surface. The spring 540 extends or retracts resulting inpotential energy being stored by the spring 540. The damper 544functions to absorb the energy resulting from the spring 540 as thespring 540 retracts and extends, i.e., the damper 544 converts theenergy stored in the spring 540 into heat. The damper 544 furtherperforms a damping function as the spring 540 is extended or retracted.By absorbing and dissipating the energy resulting from disturbancesencountered by the truck, the spring 540 and damper 544 function tosubstantially reduce impact and vibration energy from reaching theoperator standing on the floorboard 110.

The second member 536 includes a tab 536D having an opening forreceiving a cable 536E, which may be gripped by an operator to adjustthe angular position of the second member 536 relative to the wall 14D.Once the angle of the second member 536 has been adjusted, the cable istied to an element (not shown) extending from the wall 14D so as toretain the second member 536 in the set position. By changing theangular position of the second member 536, the preload on the spring 540as well as its angular position relative to the first member 532 may bevaried. When rotating the second member 536 counter-clockwise, the forceapplied by the spring 540 in a Y direction to the carriage assembly 134Aincreases. Conversely, when rotating the second member 536 clockwise,the force applied by the spring 540 in a Y direction to the carriageassembly 134A decreases.

An upper stop (not shown) is fixedly coupled to the truck main bodyframe 14 so as to limit upward movement of the floorboard 110. One ormore lower stops (not shown) are fixed to a lower surface 110D of thefloorboard 110 to limit downward movement of the floorboard 110 relativeto the base (not shown in FIG. 8) of the frame 14, i.e., the lower stopsengage the base to prevent further downward movement of the floorboard110. The upper and lower stops may be made of natural rubber, urethane,silicone or other like elastomeric type material. The stops in apreferred embodiment provide a force deflection characteristic, i.e.,they deflect by x amount when a force F is applied against the stop, asdescribed by the following polynomial equation:F=−27.88x ³+251x ²+86.7x

wherein F=force, and x=deflection.

Preferably, the floorboard 110 is located in a neutral position betweenan upper stop position, where the floorboard 110 engages the upper stopand a lower stop position, where the lower stops on the floorboard 110engage the base of the frame 14. In the illustrated embodiment, the“neutral position” is equal to a predefined position falling within arange equal to ±15% of a centered position.

When a light-weight operator is positioned on the floorboard 110, thefloorboard 110 may be spaced from the neutral position toward the upperstop. Conversely, when a heavy-weight operator is positioned on thefloorboard 110, the floorboard 110 may be spaced from the neutralposition toward the base of the frame 14. So as to allow the floorboard110 to be positioned in its neutral position subsequent to an operatorstepping onto the floorboard 110, an operator grips the cable 536E andpulls it so as to rotate the second member 536 in an appropriatedirection to change the preload on the spring 540 as well as its angularorientation such that the floorboard 110 is repositioned to its neutralposition. A mark (not shown) may be provided on a wall of the framewhich, when aligned with the floorboard 110, indicates to the operatorthat the floorboard 110 has been moved to its neutral position. It isbelieved that the floorboard 110 may accommodate an operator having aweight that falls within a substantially broad range, e.g., from about100 pounds to about 300 pounds, and yet still be moved to its neutralposition by varying the preload on the spring 440.

An operator support assembly 600 constructed in accordance with a sixthembodiment of the present invention is illustrated in FIG. 9, where likereference numerals indicate like elements. The operator support assembly600 may be incorporated into a truck similar to the one illustrated inFIG. 1 or other materials handling vehicles. The operator supportassembly 600 comprises a suspended floorboard 110 and an energyabsorbing structure 620 coupled to the truck main body frame 14 and thesuspended floorboard 110 for absorbing and dissipating at least aportion of energy resulting from disturbances encountered by the truckas it moves across a floor surface prior to the energy portion reachingthe operator standing on the suspended floorboard 110. The energyabsorbing structure 620 comprises a mast assembly 130 and a suspensionsystem 630.

The mast assembly 130 is constructed in the same manner as the oneillustrated in FIGS. 2-4. It comprises a channel 132A fixedly coupled tothe frame 14 of the truck main body 12, and a carriage assembly 134Acapable of vertical movement within the channel 132A. The carriageassembly 134A comprises a main body 136 and a floorboard support 136C.

The suspension system 630 comprises a hydraulic piston/cylinder unit640, a needle valve 650, an air charged accumulator 660 (also referredto herein as a ride accumulator) and tubing 670. A cylinder 642 of theunit 640 is fixed to the frame 14 of the truck main body 12. A pistonrod 644 of the unit 640 is bolted to the main body 136 of the carriageassembly 134A such that the piston rod 644 moves with the floorboard110. The piston rod 644 is threaded into, bolted or otherwise coupled toa piston 644A, which also forms part of the unit 640 and is movablewithin the cylinder 642. A first portion 642A of the cylinder 642, i.e.,the portion above the piston 644A, is provided with an opening 642B soas to permit air A at atmospheric pressure to enter into the cylinderportion 642A. A second portion 642C of the cylinder 642, i.e., theportion below the piston 644A, is filled with hydraulic fluid HF. Hence,the piston 644A separates the two cylinder portions 642A and 642C anddefines a barrier so as to prevent air and hydraulic fluid HF frommixing within the cylinder 642.

The needle valve 650 restricts or limits hydraulic fluid flow from thehydraulic piston/cylinder unit 640 into the air charged accumulator 660and from the air charged accumulator 660 into the unit 640.

A diaphragm 661 is provided within the accumulator 660 to separate theinterior of the accumulator 660 into a lower portion 660A and an upperportion 660B. The lower portion 660A is filled with hydraulic fluid HF,while the upper portion 660B is filled with pressurized air PA. It iscontemplated that the upper portion 660B may be filled with another gas,such as nitrogen gas. In the embodiment illustrated in FIG. 9, thequantity of the air PA in the accumulator upper portion 660B is notchanged once the upper portion 660B is pressurized during manufacturing.The pressurized air PA applies a force to the hydraulic fluid HF suchthat the fluid HF within the accumulator 660 and the cylinder 642 isunder pressure. The tubing 670 allows hydraulic fluid HF to move fromthe piston/cylinder unit 640 through the needle valve 650 into theaccumulator 660 and from the accumulator 660 through the needle valve650 into the piston/cylinder unit 640. It is contemplated that thediaphragm type accumulator illustrated in FIG. 9 may be replaced byother known types of equivalent accumulators such as piston/cylindertype or bladder type accumulators.

The floorboard support 136C is positioned beneath the floorboard 110 andsupports the floorboard 110 within the truck rider compartment. Thecarriage assembly 134A functions as the sole support for the floorboard110; hence, the floorboard 110 is suspended in the rider compartment onthe carriage assembly 134A. The floorboard 110 moves with the carriageassembly 134A. As noted above, the piston rod 644 is fixedly coupled tothe carriage assembly 134A. Hence, movement of the carriage assembly134A and the floorboard 110 is transferred to the piston rod 644 and thepiston 644A.

When a truck including the operator support assembly 600 travels over ahole, the piston 644A and piston rod 644 move upward in the cylinder642, see direction arrow A in FIG. 9. This movement causes hydraulicfluid HF to be supplied by the accumulator 660 through the needle valve650 into the cylinder second portion 642C. After hydraulic fluid HF issupplied to the cylinder second portion 642C, the piston 644A and pistonrod 644 move in the opposite direction, i.e., downward in the cylinder642, due to re-application of the weight of the operator to thefloorboard 110, causing hydraulic fluid HF to be forced in a reversedirection through the needle valve 650 into the accumulator 660. Theneedle valve 650 produces a damping effect. That is, the needle valve650 functions to convert kinetic energy of the moving pressurized fluid,i.e., the hydraulic fluid moving from the accumulator 660 through theneedle valve 650 into the cylinder 642 and from the cylinder 642 throughthe needle valve 650 into the accumulator 660, into heat. The dampingrate of the needle valve 650 is defined by the size of the openingwithin the needle valve 650 and the properties of the hydraulic fluidHF.

When the truck including the operator support assembly 600 travels overa bump, the piston 644A and piston rod 644 move downward in the cylinder642, see direction arrow B in FIG. 9. This movement causes hydraulicfluid HF to be forced from the cylinder second portion 642C through theneedle valve 650 into the accumulator 660. After hydraulic fluid HF isforced by the piston 644A through the needle valve 650 into theaccumulator 660, the pressurized air PA within the accumulator 660 actsto force hydraulic fluid in a reverse direction back through the needlevalve 650 into the cylinder 642. The needle valve 650 produces a dampingeffect in response to fluid movement. That is, the needle valve 650functions to convert kinetic energy of the moving pressurized hydraulicfluid HF, i.e., the hydraulic fluid HF moving from the cylinder 642through the needle valve 650 into the accumulator 660 and from theaccumulator 660 through the needle valve 650 into the cylinder 642, intoheat. The air and the accumulator 660 function as a spring. That is, theaccumulator 660 and the air function to store potential energy resultingfrom hydraulic fluid HF being forced from the cylinder second portion642C through the needle valve 650 into the accumulator 660 due todownward movement of the piston 644A.

By absorbing and dissipating the energy resulting from the disturbancesencountered by the truck, the suspension system 630 functions tosubstantially reduce impact and vibration energy from reaching theoperator standing on the floorboard 110.

An upper stop (not shown) is fixedly coupled to the truck main bodyframe 14 so as to limit upward movement of the floorboard 110. One ormore lower stops (not shown) are fixed to a lower surface 110D of thefloorboard 110 to limit downward movement of the floorboard 110 relativeto a base (not shown in FIG. 9) of the frame 14, i.e., the lower stopsengage the base to prevent further downward movement of the floorboard110. The upper and lower stops may be made of natural rubber, urethane,silicone or other like elastomeric type material. The stops in apreferred embodiment provide a force deflection characteristic, i.e.,they deflect by x amount when a force F is applied against the stop, asdescribed by the following polynomial equation:F=−27.88x ³+251x ²+86.7x

wherein F=force, and x=deflection.

Preferably, the floorboard 110 is located in a neutral position betweenan upper stop position, where the floorboard 110 engages the upper stopand a lower stop position, where the lower stops on the floorboard 110engage the base of the frame 14. In the illustrated embodiment, the“neutral position” is equal to a predefined position falling within arange equal to ±15% of a centered position.

Preferably, the quantity of the air PA in the accumulator 660 (or acorresponding air pressure within the accumulator 660 when an operatoris not positioned on the floorboard 110) is selected so that when anoperator, having a predetermined weight, is positioned on the floorboard110, the floorboard 110 remains within a predefined range of the neutralposition, e.g., within a range equal to +/−15% of the neutral position.For example, if the accumulator 660 is precharged to a first pressure,such as 67 pounds/inch², an operator having a weight within a firstweight range, such as from about 250 pounds to about 300 pounds, may bepositioned on the floorboard 110, with the floorboard 110 remainingwithin the predefined range of the neutral position under normaloperating conditions. As a further example, if the accumulator 660 isprecharged to a second pressure, such as 30 pounds/inch², an operatorhaving a weight within a second weight range, such as from about 100pounds to about 125 pounds, may be positioned on the floorboard 110,with the floorboard 110 remaining within the predefined range of theneutral position under normal operating conditions. Further, the size ofthe opening or orifice in the needle valve 650 and the properties of thehydraulic fluid HF are preferably selected so as to define a flow ratethrough the needle valve 650 such that the floorboard 110 is preventedfrom engaging the upper stop when the truck moves over bumps orobstructions of a size typically encountered by such trucks and furtherto allow the needle valve 650 to quickly damp out energy resulting fromdisturbances typically encountered by the truck.

An operator support assembly 700 constructed in accordance with aseventh embodiment of the present invention is illustrated in FIG. 10,where like reference numerals indicate like elements. The operatorsupport assembly 700 may be incorporated into a truck similar to the oneillustrated in FIG. 1 or other materials handling vehicles. The operatorsupport assembly 700 comprises a suspended floorboard 110 and an energyabsorbing structure 720 coupled to the truck main body frame 14 and thesuspended floorboard 110 for absorbing and dissipating at least aportion of energy resulting from disturbances encountered by the truckas it moves across a floor surface prior to the energy portion reachingthe operator standing on the suspended floorboard 110. The energyabsorbing structure 720 comprises a mast assembly 130 and a suspensionsystem 730.

The mast assembly 130 is constructed in the same manner as the oneillustrated in FIGS. 2-4. It comprises a channel 132A fixedly coupled tothe frame 14 of the truck main body 12, and a carriage assembly 134Acapable of vertical movement within the channel 132A. The carriageassembly 134A comprises a main body 136 and a floorboard support 136C.

The suspension system 730 comprises a hydraulic piston/cylinder unit640, a 2 position 4-way proportional valve 740, a ride accumulator 742,a first flow restrictor or orifice 750, a 2-way blocking type pneumaticvalve 760, a height adjust accumulator 762, a second flow restrictor ororifice 752, a 2 position 3-way solenoid valve 770, a processor 780 andtubing 790 extending between the piston/cylinder unit 640, the valves740, 760 and 770, the accumulators 742 and 762 and the orifices 750 and752. The operation of the valves 740, 760 and 770 is controlled via theprocessor 780.

The piston/cylinder unit 640 is constructed in the same manner as theone illustrated in FIG. 9. It comprises a cylinder 642 fixed to theframe 14 of the truck main body 12. A piston rod 644 of the unit 640 isbolted to the main body 136 of the carriage assembly 134A such that thepiston rod 644 moves with the floorboard 110. The piston rod 644 isthreaded into, bolted or otherwise coupled to a piston 644A, which alsoforms part of the unit 640 and is movable within the cylinder 642. Afirst portion 642A of the cylinder 642, i.e., the portion above thepiston 644A, is provided with an opening 642B so as to permit air A atatmospheric pressure to enter into the cylinder portion 642A. A secondportion 642C of the cylinder 642, i.e., the portion below the piston644A, is filled with hydraulic fluid HF.

As noted above, the operation of the 2 position 4-way proportional valve740 is controlled via the processor 780. In a first position, the valve740 is in a closed state such that hydraulic fluid is not permitted toenter or leave the cylinder second portion 642C. When in its closedstate, the valve 740 maintains the fluid volume within the cylinder 642constant so as to lock the floorboard 110 in a fixed position relativeto the frame 14 of the truck main body 12. The floorboard 110, whenlocked in a fixed position, provides an operator with a firm feel ashe/she steps into or out of the rider compartment 30. The processor 780may function to move the valve 740 to its first position when the truckis not in motion, e.g., when power is not being delivered to the firstand second driven wheels.

In a second position, the valve 740 is in an opened state to allowhydraulic fluid HF to flow from the cylinder 642 to the accumulator 742and from the accumulator 742 to the cylinder 642. The size of theopening within the valve 740 is controlled via the processor 780 suchthat the valve 740 performs a damping function. The valve opening ispreferably defined so as to effect an optimal damping function, i.e., toquickly damp out energy resulting from disturbances encountered by thetruck. In the illustrated embodiment, the processor 780 opens the valve740 when an operator selects a direction of travel such that power isprovided to the first and second driven wheels. It is preferred that theprocessor 780 open the valve 740 slowly so as to make any movement ofthe floorboard 110 upon being unlocked substantially unnoticeable to theoperator. The processor 780 may close the valve 740 so as to lock thefloorboard 110 in position when an operator is no longer depressing thepresence sensor 40.

A diaphragm 743 is provided within the ride accumulator 742 to separatethe interior of the accumulator 742 into a lower portion 742A and anupper portion 742B. The lower portion 742A of the ride accumulator 742is filled with hydraulic fluid HF, while the upper portion 742B isfilled with pressurized air PA. It is contemplated that the upperportion 742B may be filled with another gas, such as nitrogen gas. Aswill be discussed below, the quantity of air PA in the accumulator upperportion 742B may be varied. When the valve 740 is in its secondposition, the pressurized air PA in the accumulator upper portion 742Bapplies a force to the hydraulic fluid HF in the accumulator lowerportion 742A such that the pressure of the hydraulic fluid HF in theaccumulator lower portion 742A and the cylinder second portion 642C issubstantially the same. It is also noted that when the valve 740 is inits second position, tubing 790 extending between the cylinder 642, thevalve 740 and the accumulator 742 defines a path for hydraulic fluid HFto move from the piston/cylinder unit 640 through the valve 740 into theaccumulator 742 and from the accumulator 742 through the valve 740 intothe piston/cylinder unit 640. It is contemplated that the diaphragm typeaccumulator 742 may be replaced by other known types of equivalentaccumulators such as piston/cylinder type or bladder type accumulators.

As will be discussed below, when the processor 780 is not effecting afloorboard height adjustment operation, it maintains the 2-way blocktype pneumatic valve 760 in a closed state. With the valve 760 closed,pressurized air does not enter or leave the accumulator 742.

The floorboard support 136C is positioned beneath the floorboard 110 andsupports the floorboard 110 within the truck rider compartment. Thecarriage assembly 134A functions as the sole support for the floorboard110; hence, the floorboard 110 is suspended in the rider compartment onthe carriage assembly 134A. The floorboard 110 moves with the carriageassembly 134A. As noted above, the piston rod 644 is fixedly coupled tothe carriage assembly 134A. Hence, movement of the carriage assembly134A and the floorboard 110 is transferred to the piston rod 644 and thepiston 644A.

Presuming the valve 740 is in its second position and valve 760 is inits closed state, when a truck including the operator support assembly700 travels over a hole, the piston 644A and piston rod 644 move upwardin the cylinder 642, see direction arrow A in FIG. 10. This movementcauses hydraulic fluid HF to be supplied by the accumulator 742 throughthe valve 740 into the cylinder second portion 642C. After hydraulicfluid HF is supplied to the cylinder second portion 642C, the piston644A and piston rod 644 move in the opposite direction, i.e., downwardin the cylinder 642, due to re-application of the weight of the operatorto the floorboard 110, causing hydraulic fluid HF to be forced in areverse direction through the valve 740 into the accumulator 742. Asnoted above, the opening within the valve 740 is preferably defined bythe processor 780 so as to optimize damping. The valve 740 effectsdamping by converting kinetic energy of the moving pressurized fluid,i.e., the hydraulic fluid moving from accumulator 742 through the valve740 into the cylinder 642 and from the cylinder 642 through the valve740 into the accumulator 742, into heat.

Presuming again that the valve 740 is in its second position and valve760 is in its closed state, when the truck including the operatorsupport assembly 700 travels over a bump, the piston 644A and piston rod644 move downward in the cylinder 642, see direction arrow B in FIG. 10.This movement causes hydraulic fluid HF to be forced from the cylindersecond portion 642C through the valve 740 into the accumulator 742.After hydraulic fluid HF is forced by the piston 644A through the valve740 into the accumulator 742, the resulting increased air pressurewithin the accumulator 742 acts to force hydraulic fluid in a reversedirection back through the valve 740 into the cylinder 642. As notedabove, the valve 740 produces a damping effect in response to fluidmovement. That is, the valve 740 functions to convert kinetic energy ofthe moving pressurized hydraulic fluid HF, i.e., the hydraulic fluid HFmoving from the cylinder 642 through the valve 740 into the accumulator742 and from the accumulator 742 through the valve 740 into the cylinder642, into heat. The air and the accumulator 742 function as a spring.That is, the accumulator 742 and air function to store potential energyresulting from hydraulic fluid HF being forced from the cylinder secondportion 642C through the valve 740 into the accumulator 742.

An upper stop (not shown in FIG. 10) is fixedly coupled to the truckmain body frame 14 so as to limit upward movement of the floorboard 110.One or more lower stops (not shown) are fixed to a lower surface 110D ofthe floorboard 110 to limit downward movement of the floorboard 110relative to the base (not shown in FIG. 10) of the frame 14, i.e., thelower stops engage the base to prevent further downward movement of thefloorboard 110. The upper and lower stops may be made of natural rubber,urethane, silicone or other like elastomeric type material. The stops ina preferred embodiment provide a force deflection characteristic, i.e.,they deflect by x amount when a force F is applied against the stop, asdescribed by the following polynomial equation:F=−27.88x ³+251x ²+86.7x

wherein F=force, and x=deflection.

Preferably, the floorboard 110 is located in a neutral position betweenan upper stop position, where the floorboard 110 engages the upper stopand a lower stop position, where the lower stops on the floorboard 110engage the base of the frame 14. In the illustrated embodiment, the“neutral position” is equal to a predefined position falling within arange equal to ±15% of a centered position.

When a light-weight operator steps onto the floorboard 110, thefloorboard 110, after being unlocked, may move so as to be spaced fromthe neutral position toward the upper stop. Conversely, when aheavy-weight operator steps onto the floorboard 110, the floorboard 110,after being unlocked, may move so as to be spaced from the neutralposition toward the base of the frame 14. To allow the floorboard 110 tobe moved to its neutral position after an operator steps onto thefloorboard 110 and the floorboard 110 is unlocked, the processor 780effects a floorboard height adjustment operation. Such an operation iseffected in the illustrated embodiment just after the floorboard 110 isunlocked. As noted above, the floorboard 110 may be unlocked when anoperator, standing on the floorboard 110, selects a direction of travelfor the truck, i.e., when power is provided to the first and seconddriven wheels.

A sensor 744, such as a conventional linear position sensor, fixed tothe main body frame 14, may be provided to detect when the floorboard isspaced from its predefined neutral position. Alternatively, switches,such as conventional microswitches, may be provided to sense when thefloorboard 110 has moved away from its neutral position. As will bediscussed further below, the processor 780, when effecting a floorboardheight adjustment operation, controls the operation of the 2 position4-way proportional valve 740, the 2-way blocking type pneumatic valve760, and the 2 position 3-way solenoid valve 770 to move the floorboard110 to its neutral position. It is believed that the floorboard 110 mayaccommodate an operator having a weight that falls within asubstantially broad range, e.g., from about 100 pounds to about 300pounds, and yet still be moved to its neutral position after theoperator steps onto the floorboard 110 and the floorboard 110 isunlocked.

When the processor 780 determines during a floorboard height adjustmentoperation, based on signals generated by the sensor 744, that thefloorboard 110 needs to be moved upward relative to the truck main bodyframe 14, the processor 780 causes pressurized air to be added to theaccumulator 742. When the processor 780 determines during a floorboardheight adjustment operation, based on signals generated by the sensor744, that the floorboard 110 needs to be moved downward relative to thetruck main body frame 14, the processor 780 releases pressurized airfrom the accumulator 742. Apparatus and process steps for addingpressurized air to or releasing pressurized air from the accumulator 742will now be discussed.

When the processor 780 is not effecting a floorboard height adjustmentoperation, it maintains the 2-way block type pneumatic valve 760 in aclosed state. With the valve 760 closed, pressurized air does not enteror leave the accumulator 742.

A diaphragm 763 is provided within the height adjust accumulator 762 toseparate the interior of the accumulator 762 into a lower portion 762Aand an upper portion 762B. As will be discussed further below, the lowerportion 762A of the accumulator 762 may be filled with hydraulic fluidHF, while the upper portion 762B of the accumulator 762 may containpressurized air PA. It is contemplated that the upper portion 762B maycontain another gas, such as nitrogen gas. It is further contemplatedthat the diaphragm type accumulator 762 may be replaced by other knowntypes of equivalent accumulators such as piston/cylinder type or bladdertype accumulators. For example, a piston/cylinder type accumulator maybe beneficial as they typically have a range of usable volume which isgreater than that of a diaphragm type accumulator.

When the processor 780 is not effecting a floorboard height adjustmentoperation, it maintains the 2 position 3-way solenoid valve 770 in afirst position to allow hydraulic fluid contained in the lower portion762A of the accumulator 762 to drain from the lower portion 762A throughthe valve 770 into a hydraulic fluid reservoir 784.

The total amount of air in the accumulators 742 and 762 is fixed.However, air may be moved from the ride accumulator 742 to the heightadjust accumulator 762 and vice versa. Hence, the portion of the air inthe accumulator 742, which portion comprises part of the total quantityof air in the accumulators 742 and 762, may be varied.

When the processor 780 determines during a floorboard height adjustmentoperation, based on signals generated by the sensor 744, that thefloorboard 110 needs to be moved upward relative to the truck main bodyframe 14, the processor 780 initially maintains the 2-way block typepneumatic valve 760 in its closed state. With the valve 760 in itsclosed state, the processor 780 causes the 2 position 3-way solenoidvalve 770 to move to a second position. When in its second position, thevalve 770 allows hydraulic fluid HF provided by a source of pressurizedhydraulic fluid 782, such as a hydraulic pump, to pass through the valve770 into the lower portion 762A of the accumulator 762. Pressurizedhydraulic fluid HF entering the accumulator 762 causes the pressure ofthe air within the upper portion 762B of the accumulator 762 toincrease. Just after the valve 770 is moved to its second position, theprocessor 780 causes the 2-way block type pneumatic valve 760 to move toits open state, resulting in pressurized air flowing through the valve760 into the ride accumulator 742.

An increase in the air quantity within the upper portion 742B of theaccumulator 742 results in an increase in hydraulic fluid pressurewithin both the accumulator 742 and the cylinder 642. In the illustratedembodiment, the valve 740 is opened prior to the processor 780 effectingthe floorboard height adjustment operation as the height adjustmentoperation occurs just after the floorboard 110 is unlocked by openingthe valve 740. The increased fluid quantity within the cylinder 642causes the floorboard 110 to move upward relative to the truck main bodyframe 14. Once the floorboard 110 is raised to its neutral position, assensed by the sensor 744, the processor 780 causes the valve 760 to moveto its closed state and subsequently causes the valve 770 to move to itsfirst position. As noted above, when the valve 770 is moved to its firstposition, hydraulic fluid drains from the lower portion 762A of theaccumulator 762 through the valve 770 into a hydraulic fluid reservoir784.

The first flow restrictor or orifice 750 limits the rate at whichpressurized air passes from the height adjust accumulator 762 to theride accumulator 742 and the second flow restrictor or orifice 752limits the rate at which pressurized hydraulic fluid moves into thelower portion 762A of the accumulator 762. By restricting the flow ofair through the first restrictor 750 and the flow of fluid through thesecond restrictor 752, the rate at which the floorboard 110 is raised islimited to an acceptable value.

When the processor 780 determines during a floorboard height adjustmentoperation, based on signals generated by the sensor 744, that thefloorboard 110 needs to be moved downward relative to the truck mainbody frame 14, the processor 780 moves the 2-way block type pneumaticvalve 760 to its open state. The valve 770 is normally in its firstposition. The processor 780 does not change the position of the valve770 when the floorboard 110 is lowered. Because the valve 770 is in itsfirst position, little if any hydraulic fluid HF is contained in thelower portion 762A of the accumulator 762. With little or no hydraulicfluid provided in the accumulator lower portion 762A, the air pressurewithin the upper portion 762B of the accumulator 762 is low and,typically, is substantially lower than the air pressure within the upperportion 742B of the accumulator 742. Hence, once the valve 760 is movedto its open state, pressurized air is released from the upper portion742B of the accumulator 742 and moves into the upper portion 762B of theaccumulator 762. Once the floorboard 110 is lowered to its neutralposition, as sensed by the sensor 744, the processor 780 causes thevalve 760 to move to its closed state.

The first flow restrictor or orifice 750 limits the rate at whichpressurized air exits the ride accumulator 742. By restricting the flowof air through the first restrictor 750, the rate at which thefloorboard 110 is lowered falls within an acceptable range, i.e., thefloorboard 110 is not lowered too quickly.

An operator support assembly 800 constructed in accordance with aneighth embodiment of the present invention is illustrated in FIG. 11,where like reference numerals indicate like elements. The operatorsupport assembly 800 may be incorporated into a truck similar to the oneillustrated in FIG. 1 or other materials handling vehicles. The operatorsupport assembly 800 comprises a suspended floorboard 110 and an energyabsorbing structure 820 coupled to the truck main body frame 14 and thesuspended floorboard 110 for absorbing and dissipating at least aportion of energy resulting from disturbances encountered by the truckas it moves across a floor surface prior to the energy portion reachingthe operator standing on the suspended floorboard 110. The energyabsorbing structure 820 comprises a mast assembly 130 and a suspensionsystem 830.

The mast assembly 130 is constructed in the same manner as the oneillustrated in FIGS. 2-4. It comprises a channel 132A fixedly coupled tothe frame 14 of the truck main body 12, and a carriage assembly 134Acapable of vertical movement within the channel 132A. The carriageassembly 134A comprises a main body 136 and a floorboard support 136C.

The suspension system 830 comprises a hydraulic piston/cylinder unit640, a needle valve 650, an air charged accumulator 660, a two-waynormally closed poppet type valve 832, a 2 position 3-way solenoid valve770, an orifice 834, a processor 880 and tubing 836 extending betweenthe piston/cylinder unit 640, the valves 650, 832 and 770, theaccumulator 660 and the orifice 834. The operation of the valves 832 and770 is controlled via the processor 880.

The piston/cylinder unit 640, needle valve 650 and air chargedaccumulator 660 are constructed in essentially the same manner as theunit 640, valve 650 and accumulator 660 illustrated in FIG. 9.

The floorboard support 136C is positioned beneath the floorboard 110 andsupports the floorboard 110 within the truck rider compartment. Thecarriage assembly 134A functions as the sole support for the floorboard110; hence, the floorboard 110 is suspended in the rider compartment onthe carriage assembly 134A. The floorboard 110 moves with the carriageassembly 134A. As noted above, the piston rod 644 is fixedly coupled tothe carriage assembly 134A. Hence, movement of the carriage assembly134A and the floorboard 110 is transferred to the piston rod 644 and thepiston 644A.

When a truck including the operator support assembly 800 travels over ahole, the piston 644A and piston rod 644 move upward in the cylinder642, see direction arrow A in FIG. 11. This movement causes hydraulicfluid HF to be supplied by the accumulator 660 through the needle valve650 into the cylinder second portion 642C. After hydraulic fluid HF issupplied to the cylinder second portion 642C, the piston 644A and pistonrod 644 move in the opposite direction, i.e., downward in the cylinder642, due to re-application of the weight of the operator to thefloorboard 110, causing hydraulic fluid HF to be forced in a reversedirection through the needle valve 650 into the accumulator 660. Theneedle valve 650 produces a damping effect. That is, the needle valve650 functions to convert kinetic energy of the moving pressurized fluid,i.e., the hydraulic fluid moving from the accumulator 660 through theneedle valve 650 into the cylinder 642 and from the cylinder 642 throughthe needle valve 650 into the accumulator 660, into heat. The dampingrate of the needle valve 650 is defined by the size of the openingwithin the needle valve 650 and the properties of the hydraulic fluidHF.

When the truck including the operator support assembly 800 travels overa bump, the piston 644A and piston rod 644 move downward in the cylinder642, see direction arrow B in FIG. 11. This movement causes hydraulicfluid HF to be forced from the cylinder second portion 642C through theneedle valve 650 into the accumulator 660. After hydraulic fluid HF isforced by the piston 644A through the needle valve 650 into theaccumulator 660, the pressurized air PA within the accumulator 660 actsto force hydraulic fluid in a reverse direction back through the needlevalve 650 into the cylinder 642. The needle valve 650 produces a dampingeffect in response to fluid movement. That is, the needle valve 650functions to convert kinetic energy of the moving pressurized hydraulicfluid HF, i.e., the hydraulic fluid HF moving from the cylinder 642through the needle valve 650 into the accumulator 660 and from theaccumulator 660 through the needle valve 650 into the cylinder 642, intoheat. The air and the accumulator 660 function as a spring. That is, theaccumulator 660 and the air function to store potential energy resultingfrom hydraulic fluid HF being forced from the cylinder second portion642C through the needle valve 650 into the accumulator 660 due todownward movement of the piston 644A.

By absorbing and dissipating the energy resulting from the disturbancesencountered by the truck, the suspension system 830 functions tosubstantially reduce impact and vibration energy from reaching theoperator standing on the floorboard 110.

An upper stop (not shown) is fixedly coupled to the truck main bodyframe 14 so as to limit upward movement of the floorboard 110. One ormore lower stops (not shown) are fixed to a lower surface 110D of thefloorboard 110 to limit downward movement of the floorboard 110 relativeto a base (not shown in FIG. 11) of the frame 14, i.e., the lower stopsengage the base to prevent further downward movement of the floorboard110. The upper and lower stops may be made of natural rubber, urethane,silicone or other like elastomeric type material. The stops in apreferred embodiment provide a force deflection characteristic, i.e.,they deflect by x amount when a force F is applied against the stop, asdescribed by the following polynomial equation:F=−27.88x ³+251x ²+86.7x

wherein F=force, and x=deflection.

Preferably, the floorboard 110 is located in a neutral position betweenan upper stop position, where the floorboard 110 engages the upper stopand a lower stop position, where the lower stops on the floorboard 110engage the base of the frame 14. In the illustrated embodiment, the“neutral position” is equal to a predefined position falling within arange equal to ±15% of a centered position.

When a light-weight operator steps onto the floorboard 110, thefloorboard 110 may move so as to be spaced from the neutral positiontoward the upper stop. Conversely, when a heavy-weight operator stepsonto the floorboard 110, the floorboard 110 may move so as to be spacedfrom the neutral position toward the base of the frame 14. To allow thefloorboard 110 to be moved to its neutral position after an operatorsteps onto the floorboard 110, the processor 880 effects a floorboardheight adjustment operation. Such an operation is effected in theillustrated embodiment just after an operator, standing on thefloorboard 110, selects a direction of travel for the truck, i.e., whenpower is provided to the first and second driven wheels. Alternatively,a floorboard height adjustment operation may be effected just after anoperator enters the operator's compartment and activates the presencesensor 40.

A sensor 744, such as a conventional linear position sensor, fixed tothe main body frame 14, may be provided to detect when the floorboard110 is spaced from its predefined neutral position. Alternatively,switches, such as conventional microswitches, may be provided to sensewhen the floorboard 110 has moved away from its neutral position. Aswill be discussed further below, the processor 880, when effecting afloorboard height adjustment operation, controls the operation of thetwo-way normally closed poppet type valve 832 and the 2 position 3-waysolenoid valve 770 to move the floorboard 110 to its neutral position.It is believed that the floorboard 110 may accommodate an operatorhaving a weight that falls within a substantially broad range, e.g.,from about 100 pounds to about 300 pounds, and yet still be moved to itsneutral position after the operator steps onto the floorboard 110 andthe floorboard 110 is unlocked.

When the processor 880 determines during a floorboard height adjustmentoperation, based on signals generated by the sensor 744, that thefloorboard 110 needs to be moved upward relative to the truck main bodyframe 14, the processor 880 causes pressurized fluid HF to be added tothe lower portion 660A of the accumulator 660 and the cylinder secondportion 642C. When the processor 880 determines during a floorboardheight adjustment operation, based on signals generated by the sensor744, that the floorboard 110 needs to be moved downward relative to thetruck main body frame 14, the processor 880 causes pressurized fluid HFto be released from the accumulator lower portion 660A and the cylindersecond portion 642C. Apparatus and process steps for adding pressurizedfluid to or releasing pressurized fluid HF from the accumulator 660 willnow be discussed.

When the processor 880 is not effecting a floorboard height adjustmentoperation, it maintains the 2 position 3-way solenoid valve 770 in afirst position to allow hydraulic fluid to pass through the valve 770 toa hydraulic fluid reservoir 784.

When the processor 880 determines during a floorboard height adjustmentoperation, based on signals generated by the sensor 744, that thefloorboard 110 needs to be moved upward relative to the truck main bodyframe 14, the processor 880 causes the 2 position 3-way solenoid valve770 to move to its second position. When in its second position, thevalve 770 allows hydraulic fluid HF provided by a source of pressurizedhydraulic fluid 782, such as a hydraulic pump, to pass through the valve770. The pressurized hydraulic fluid HF also passes through the valve832 and enters into the lower portion 660A of the accumulator 660 aswell as the cylinder 642. The increased fluid quantity in the cylinder642 causes the floorboard 110 to move upward relative to the truck mainbody frame 14. Once the floorboard 110 is raised to its neutralposition, as sensed by the sensor 744, the processor 880 causes thevalve 770 to return to its first position such that pressurized fluid isno longer provided to the accumulator 660 and the cylinder 642. Thenormally closed valve 832 is not actuated by the processor 880 when thefloorboard 110 is being raised. When the valve 832 is not actuated,i.e., in its normally closed state, the valve 832 only allowspressurized fluid to pass through it and enter the accumulator 660 butdoes not allow pressurized fluid to exit the accumulator 660.

The orifice 834 limits the rate at which pressurized hydraulic fluid HFmoves into the lower portion 660A of the accumulator 660 and thecylinder 642. By restricting the flow of fluid through the orifice 834,the rate at which the floorboard 110 is raised is limited to anacceptable value.

When the processor 880 determines during a floorboard height adjustmentoperation, based on signals generated by the sensor 744, that thefloorboard 110 needs to be moved downward relative to the truck mainbody frame 14, the processor 880 moves the normally closed valve 832 toits opened state, i.e., the valve 832 is actuated. The valve 832 is onlyactuated when the floorboard 110 is being lowered. Hence, during allother times, including normal operation of the truck, the valve 832remains in its normally closed state. The processor 880 does not changethe position of the valve 770 when the floorboard 110 is lowered, i.e.,the valve 770 remains in its first position. Once the valve 832 is movedto its opened state, pressurized fluid is released from the lowerportion 660A of the accumulator 660 and the cylinder 642, therebyreducing the fluid quantity in the cylinder 642. The reduced fluidquantity in the cylinder 642 causes the floorboard 110 to move downwardrelative to the truck main body frame 14. Once the floorboard 110 islowered to its neutral position, as sensed by the sensor 744, theprocessor 880 causes the valve 832 to move to its normally closed state.

The orifice 834 again limits the rate at which pressurized fluid exitsthe accumulator 660. By restricting the flow of fluid through theorifice 834, the rate at which the floorboard 110 is lowered fallswithin an acceptable range, i.e., the floorboard 110 is not lowered tooquickly.

An operator support assembly 900 constructed in accordance with a ninthembodiment of the present invention is illustrated in FIGS. 12-17, wherelike reference numerals indicate like elements. The operator supportassembly 900 may be incorporated into a truck similar to the oneillustrated in FIG. 1 or other materials handling vehicles. The operatorsupport assembly 900 comprises a suspended floorboard 910, which definesa floor in the truck rider compartment, and an energy absorbingstructure 920. In the illustrated embodiment, the operator supportassembly 900 may comprise a single assembly, which may be assembled as asingle unit prior to being mounted to the truck main body frame 14.

The energy absorbing structure 920 is coupled to the truck main bodyframe 14 and the suspended floorboard 910 for absorbing and dissipatingat least a portion of energy resulting from disturbances encountered bythe truck 10 as it moves across a floor surface prior to the energyportion reaching the operator standing on the suspended floorboard 910.The disturbances may result from the truck 10 passing over acontinuously uneven surface, or moving over large bumps or sharp dropsin the surface. In the embodiment illustrated in FIGS. 12-17, the energyabsorbing structure 920 comprises a mast assembly 930, first and secondtension springs 940 and 942, a damper 944, and spring preload adjustingstructure 950.

Referring now to FIGS. 16 and 17, the mast assembly 930 includes first,second, third and fourth guide track blocks 932A-932D, which are fixedlycoupled, such as by welds, to a support plate 960. The support plate 960is fastened to the truck frame 14 of the truck main body 12 via bolts960A. The mast assembly 930 further comprises a carriage assembly 934capable of vertical movement along the track blocks 932A-932D, see FIGS.12-17. In the illustrated embodiment, the carriage assembly 934comprises a main body 936 and first, second, third and fourth front loadbearings 936A-936D and first and second side load bearings 936E and936F, see FIG. 15. The front load bearings 936A-936D are received inguide tracks 933A-933D defined in the guide track blocks 932A-932D so asto allow the main body 936 to move vertically along the track blocks932A-932D and relative to the fixed support plate 960. The first sideload bearing 936E is received between opposing center plates 935A and935B of the guide track blocks 932A and 932B, respectively, see FIG. 16.The second side load bearing 936F is received between opposing centerplates 935C and 935D of the guide track blocks 932C and 932D,respectively.

The carriage assembly 934 further comprises a floorboard support 937,which is fixedly coupled, such as by welds, to the main body 936 formovement with the main body 936. The floorboard support 937 ispositioned beneath the floorboard 910 and supports the floorboard 910within the rider compartment 30. The floorboard support 937 functions asthe sole support for the floorboard 910; hence, the floorboard 910 issuspended in the rider compartment 30 on the support 937 and movesvertically with the floorboard support 937 and the main body 936.Preferably, the floorboard 910 is fixedly coupled to the support 937.

As illustrated in FIG. 12, the first and second tension springs 940 and942 are connected to side plates 936G and 936H, respectively, extendingfrom the main body 936. The first and second tension springs 940 and 942are also connected to a yoke 952 forming part of the spring preloadadjusting structure 950. The damper 944 may comprise a dampercommercially available from Stabilus (Germany) under the productdesignation Stab-O-Shoc. From mathematical calculations, it is believedthat the damper 944 should have a linear damping rate of 4-10pounds-second/inch for compression, 10-20 pounds-second/inch forextension, and a stroke length between about 1 inch to about 5 inchesand preferably about 2 inches. The damper 944 comprises a piston rod944A fixedly coupled to the main body 936. A cylinder 944B of the damper944 is fixedly coupled to a block 962, which, in turn, is fixed to thesupport plate 960. As noted above, the support plate 960 is fixed to thetruck main body frame 14. The cylinder 944B may contain a fluid such asair or oil and a piston (not shown) coupled to the piston rod 944A,wherein the piston may have a small opening through which the fluidflows.

The springs 940 and 942 function to absorb at least a portion of energyresulting from disturbances encountered by the truck 10 as it movesalong a floor surface. The springs 940 and 942 extend (for a bump) andretract (for a hole) in response to receiving kinetic energy and, assuch, store the kinetic energy as potential energy. The damper 944functions to absorb the energy released from the springs 940 and 942 asthe springs 940 and 942 return to an initial position followingextension or retraction, i.e., the damper 944 converts the kineticenergy into heat. The damper 944 further performs a damping function asthe springs 940 and 942 are extended or retracted. By absorbing anddissipating the energy resulting from disturbances encountered by thetruck 10, the springs 940 and 942 and the damper 944 function tosubstantially reduce impact and vibration energy from reaching theoperator standing on the floorboard 910.

A lever 954, also forming part of the preload adjusting structure 950,is pivotally coupled to the fixed support plate 960 at a pivotconnection 954A, see FIG. 16. An adjust-assist spring 956 is coupled tothe fixed support plate 960 and a first end 954B of the lever 954. Theyoke 952 is pivotally coupled to the lever 954 at a pivot connection954C. A U-shaped engaging member (not shown) is provided on a surface ofthe lever 954 facing the fixed support plate 960 at or near a second end954D of the lever 954 and is capable of engaging one of a plurality ofrecesses 964A provided in an adjust-setting plate 964 fixed to thesupport plate 960. An operator is capable of gripping the lever at thelever second end 954D so as to adjust the tension on the springs 940 and944. The adjust-assist spring 956 applies a force to the lever 954 tohelp an operator overcome the forces applied to the yoke 952 by thesprings 940 and 942. By moving the lever 954 in a direction away fromthe main body 936, the first and second springs 940 and 942 areextended, i.e., lengthened, so as to increase a preload on each spring940, 942, see FIG. 13 where the lever 954 is positioned at its uppermostposition such that the preload on the springs 940 and 942 is at itsgreatest value. By moving the lever 954 in a direction toward the mainbody 936, the preload on the springs 940 and 942 is reduced, see FIG. 12where the lever 954 is positioned at its lowermost position such thatthe preload on the springs 940 and 942 is at its lowest value.

An upper stop block 958 with first and second upper stops 958A and 958Bis fixedly coupled to the fixed support plate 960 so as to limit upwardmovement of the carriage assembly 934, see FIGS. 12 and 13. First andsecond lower stops 959A and 959B are fixed to a top plate 9361 of themain body 936 and are capable of engaging the first and second guidetrack blocks 932A and 932B so as to limit downward movement of thecarriage assembly 934, see FIGS. 14 and 15. The upper and lower stopsmay be made of natural rubber, urethane, silicone or other likeelastomeric type material. The stops in a preferred embodiment provide aforce deflection characteristic, i.e., they deflect by x amount when aforce F is applied against the stop, as described by the followingpolynomial equation:F=−27.88x ³+251x ²+86.7x

wherein F=force, and x=deflection.

Preferably, the position of the floorboard 910 is located in a neutralposition between an upper stop position where the carriage assembly 934engages the upper stops 958A and 958B and a lower stop position wherethe lower stops 959A and 959B engage the first and second track blocks932A and 932B. In the illustrated embodiment, the “neutral position” isequal to a predefined position falling within a range equal to ±15% of acentered position. That is, the neutral position is a predefinedposition which may comprise a midway position between the upper andlower stop positions or may be defined by another position fallingwithin the range of ±15% of the midway or centered position. The maximumdistance that the floorboard 910 moves between its upper and lower stoppositions may be from about 1 inch to about 5 inches and preferably isabout 2 inches.

When a light-weight operator is positioned on the floorboard 910, thefloorboard 910 may be spaced from the neutral position toward the upperstops 958A and 958B. Conversely, when a heavy-weight operator ispositioned on the floorboard 910, the floorboard 910 may be spaced fromthe neutral position in a direction away from the upper stops 958A and958B. The operator preferably makes an appropriate adjustment via thelever 954 to vary the preload on the springs 940 and 942 such that thefloorboard 910 is positioned in its neutral position when the operatoris standing on the floorboard 910. A visual mark (not shown) may beprovided on the support plate 960, which, when the floorboard 910 isaligned with the mark, indicates to the operator that the floorboard isin its neutral position.

It is preferred that the operator support assembly 900 have a naturalfrequency between about 1.5 and about 2.5 Hz. It is further preferredthat the floorboard 910 typically move only within a range of positionswell within its upper and lower stop positions during normal operationof the truck 10. It is believed that the energy absorbing structure 920coupled to the floorboard 910 supporting an operator having a weightbetween about 100 pounds and 300 pounds and capable of achieving thesetwo objectives may comprise first and second springs 940 and 942 havinga relaxed length (prior to being coupled to the side plates 936G and936H and the yoke 952) of from about 8 inches to about 11 inches, and aspring rate of from about 25 pounds/inch to about 200 pounds/inch.

An operator support assembly 1000 constructed in accordance with a tenthembodiment of the present invention is illustrated in FIGS. 18-21, wherelike reference numerals indicate like elements. The operator supportassembly 1000 may be incorporated into a truck similar to the oneillustrated in FIG. 1 or other materials handling vehicles. The operatorsupport assembly 1000 comprises a suspended floorboard (not shown, butis substantially the same as the floorboard 910 illustrated in phantomin FIG. 12 and will be referred to hereinafter as floorboard 910), whichdefines a floor in the truck rider compartment, and an energy absorbingstructure 1020. In the illustrated embodiment, the operator supportassembly 1000 may comprise a single assembly, which may be assembled asa single unit prior to being mounted to the truck main body frame 14.

The energy absorbing structure 1020 is coupled to the truck main bodyframe 14 and the suspended floorboard 910 for absorbing and dissipatingat least a portion of energy resulting from disturbances encountered bythe truck 10 as it moves across a floor surface prior to the energyportion reaching the operator standing on the suspended floorboard 910.The disturbances may result from the truck 10 passing over acontinuously uneven surface, or moving over large bumps or sharp dropsin the surface. In the embodiment illustrated in FIGS. 18-21, the energyabsorbing structure 1020 comprises a mast assembly 930, first and secondtension springs 940 and 942, a damper 944, and spring preload adjustingstructure 1050. The mast assembly 930, the first and second springs 940and 940 and the damper 944 are constructed in substantially the samemanner as the mast assembly 930, the springs 940 and 942 and the damper944 of the embodiment of FIGS. 12-17. The mast assembly 930 comprisesfirst, second, third and fourth guide track blocks 932A-932D andcarriage assembly 934, see FIGS. 18 and 21. The carriage assembly 934comprises main body 936, first, second, third and fourth front loadbearings 936A-936D, first and second side load bearings 936E and 936Fand floorboard support 937, see FIGS. 15 and 18.

The first and second tension springs 940 and 942 are connected to a yoke1052 forming part of the spring preload adjusting structure 1050 as wellas to the main body side plates 936G and 936H, see FIG. 18.

A lever 1054, also forming part of the preload adjusting structure 1050,is pivotally coupled to the fixed support plate 960 at a pivotconnection 1054A. An adjust-assist spring 1055 is coupled to the fixedsupport plate 960 and a first end 1054G of the lever 1054. A motor 1056is provided having a main body 1056B pivotally coupled to the supportplate 960 at a pivot connection 1056C and a threaded screw 1056D whichengages a threaded block 1059 pivotally connected to the lever 1054 at apivot connection 1056E. The yoke 1052 is pivotally coupled to the lever1054 at a pivot connection 1054F. The motor 1056 is capable of rotatingthe screw 1056D so as to move the block 1059 toward and away from themotor main body 1056B, which, in turn, causes the lever 1054 to pivot.The lever 1054 is capable of pivoting between a maximumcounter-clockwise position, as viewed in FIGS. 18-20, where a second end1054H of the lever 1054 engages and actuates a first limit switch 1057A,and a maximum clockwise position, as viewed in FIG. 21, where anintermediate portion 10541 of the lever 1054 engages and actuates asecond limit switch 1057B. When the lever 1054 is rotatedcounter-clockwise, the first and second springs 940 and 942 areextended, i.e., lengthened, so as to increase a preload on each spring940, 942. The adjust-assist spring 1055 applies a force to the lever1054 in a direction away from the motor 1056 so as to assist the motor1056 in overcoming the forces applied by the springs 940 and 942 to theyoke 1052 when the motor 1056 is actuated to rotate the lever 1054counter-clockwise. When the lever 1054 is rotated clockwise, the preloadon the first and second springs 940 and 942 is reduced.

When the lever second end 1054H engages the first limit switch 1057A,the preload on the springs 940 and 942 is at its greatest value. Whenthe lever intermediate portion 10541 engages the second limit switch1057B, the preload on the springs 940 and 942 is at its lowest value.Actuation of either the first limit switch 1057A or the second limitswitch 1057B by the lever 1054 deactivates the motor 1056.

Just as in the embodiment illustrated in FIGS. 12-17, an upper stopblock 958 with first and second upper stops 958A and 958B is fixedlycoupled to the fixed support plate 960 so as to limit upward movement ofthe carriage assembly 934. Also, just as in the embodiment of FIGS.12-17, first and second lower stops 959A and 959B are fixed to the topplate 9361 of the main body 936 and are capable of engaging the firstand second guide track blocks 932A and 932B so as to limit downwardmovement of the carriage assembly 934, see FIGS. 15, 18 and 21. Theupper and lower stops may be made of natural rubber, urethane, siliconeor other like elastomeric type material. The stops in a preferredembodiment provide a force deflection characteristic, i.e., they deflectby x amount when a force F is applied against the stop, as described bythe following polynomial equation:F=−27.88x ³+251x ²+86.7x

wherein F=force, and x=deflection.

Preferably, the position of the floorboard 910 is located in a neutralposition between an upper stop position where the carriage assembly 934engages the upper stops 958A and 958B and a lower stop position wherethe lower stops 959A and 959B engage the first and second track blocks932A and 932B. In the illustrated embodiment, the “neutral position” isequal to a predefined position falling within a range equal to ±15% of acentered position. That is, the neutral position is a predefinedposition which may comprise a midway position between the upper andlower stop positions or may be defined by another position fallingwithin the range of ±15% of the midway or centered position. The maximumdistance that the floorboard 910 moves between its upper and lower stoppositions may be from about 1 inch to about 5 inches and preferably isabout 2 inches.

When a light-weight operator is positioned on the floorboard 910, thefloorboard 910 may be spaced from the neutral position toward the upperstops 958A and 958B. Conversely, when a heavy-weight operator ispositioned on the floorboard 910, the floorboard 910 may be spaced fromthe neutral position in a direction away from the upper stops 958A and958B.

It is contemplated that the position of the floorboard 910 may beadjusted automatically during a height adjustment operation or manually.An automatic floorboard height adjustment operation may be effected justafter an operator enters the operator's compartment 30 and activates thepresence sensor 40. Alternatively, a floorboard height adjustmentoperation may be effected just after an operator, standing on thefloorboard, selects a direction of travel for the truck, i.e., whenpower is provided to the first and second driven wheels.

For automatic adjustment during a floorboard height adjustmentoperation, a first sensor 1100 is provided for detecting the position ofthe carriage assembly 934 and the floorboard 910 relative to a desiredneutral position or the support plate 960. The sensor 1100 comprises apotentiometer 1102 coupled to the support plate 960 and a rocker arm1104 coupled to the potentiometer 1102 and the main body side plate936G, see FIG. 18. The rocker arm 1104 moves with the carriage assemblymain body 936 such that the sensor 1100 senses the position of thecarriage assembly 934 and the floorboard 910. In FIG. 18, the carriageassembly 934 is in its uppermost position where it engages upper stops958A and 058B. In FIG. 19, the carriage assembly 934 is in anintermediate position and in FIG. 20, the carriage assembly 934 is inits lowermost position.

When in the automatic adjust mode, which mode may be selected by anoperator via a switch (not shown) or the like provided in the ridercompartment 30, the preload on the springs 940 and 942 is automaticallyvaried during a floorboard height adjustment operation so as to positionthe floorboard 910, with an operator thereon, in the neutral position.The sensor 1100 generates position signals to a controller (not shown)indicative of the location of the floorboard 910 relative to its neutralposition. In response to receiving the position signals from the sensor1100, the controller generates control signals to the motor 1056 causingthe motor 1056 to rotate the screw 1056D so as to pivot the lever 1054in an appropriate direction to vary the preload on the springs 940 and942 such that the floorboard 910, with the operator standing on it, isreturned to the neutral position. Hence, so as to allow the floorboard910 to be moved to the neutral position during a floorboard heightadjustment operation, the motor 1056 is actuated via the controllerduring the floorboard height adjustment operation in response toposition signals generated by the sensor 1100 to vary the preload on thesprings 940 and 942 such that the floorboard 910 is repositioned to itsneutral position.

In the manual adjust mode, the operator may vary the preload on thesprings 940 and 942 via an adjustment knob or switch (not shown) in therider compartment 30. To give the floorboard 910 a “softer” feel whenstanding on the floorboard 910, the operator may vary the position ofthe adjustment knob to cause the motor 1056 to move the lever 1054 in aclockwise direction, as viewed in FIG. 18, so as to reduce the preloadon the springs 940 and 942. To give the floorboard 910 a “firmer” feelwhen standing on the floorboard 910, the operator may vary the positionof the adjustment knob so as to cause the motor 1056 to move the lever1054 in a counter-clockwise direction, as viewed in FIG. 18, so as toincrease the preload on the springs 940 and 942. Based on the adjustmentselected by the operator, the floorboard 910 may or may not be locatedin its neutral position when the operator is standing on the floorboard910. In the manual adjust mode, the controller disregards the positionsignals generated by the first sensor 1100.

A second sensor 1110 may be provided for detecting the position of thelever 1054. The sensor 1110 comprises a potentiometer 1112 coupled tothe support plate 960 and a rocker arm 1114 coupled to the potentiometer1112 and the lever 1054, see FIG. 18. The rocker arm 1114 is rotated bythe lever 1054 when the lever 1054 is pivoted by the motor 1056 suchthat the sensor 1110 senses the position of the lever 1054 and generateslever position signals to the controller. In response to receiving thesignals generated by the sensor 1110, the controller determines theposition of the lever 1054 and, hence, the preload on the springs 940and 942. The controller may activate a display (not shown) within therider compartment 30 so as to indicate to the operator the currentpreload on the springs 940 and 942, e.g., firm, soft or an intermediatecondition between firm and soft. During the automatic mode, thecontroller may disregard the lever position signals generated by thesecond sensor 1110. Other position sensing devices may be employed inplace of the switches 1057A, 1057B and the sensor 1110. For example, anencoder or potentiometer associated with the motor screw may beemployed.

It is preferred that the operator support assembly 1000 have a naturalfrequency between about 1.5 and about 2.5 Hz. It is further preferredthat the floorboard 910 typically move only within a range of positionswell within its upper and lower stop positions during normal operationof the truck 10. It is believed that the energy absorbing structure 1020coupled to the floorboard 910 supporting an operator having a weightbetween about 100 pounds and 300 pounds and capable of achieving thesetwo objectives may comprise first and second springs 940 and 942 havinga relaxed length (prior to being coupled to the side plates 936G and936H and the yoke 1052) of from about 8 inches to about 11 inches, and aspring rate of from about 25 pounds/inch to about 200 pounds/inch.

One or more electromagnets (not shown) may be mounted to the supportplate 960 and positioned adjacent the carriage assembly main body 936.When power is provided to the electromagnets, the electromagnetsfunction to releasably lock the carriage assembly main body 936 and,hence, the floorboard 910, to the support plate 960 and the truck frame14. The electromagnets may be activated to lock the floorboard 910 tothe support plate 960 so as to provide an operator with a firm feel asthe operator steps into or out of the rider compartment. It is alsocontemplated that the one or more electromagnets may be replaced with asolenoid having a reciprocating piston. The solenoid is fixed to thesupport plate 960. A bore is provided in the carriage assembly main body936 to receive the solenoid piston when the solenoid is actuated toextend the piston. To lock the floorboard 910 to the support plate 960,the solenoid is actuated to extend the piston such that it engages thebore in the carriage main body 936. Once an operator has entered therider compartment 30, and power is provided to the driven wheels, thesolenoid may be actuated to retract the piston such that it exits thebore in the carriage assembly main body 936 so as to allow the carriageassembly 934 to move relative to the support plate 960.

An operator support assembly 1200 constructed in accordance with aneleventh embodiment of the present invention is illustrated in FIG. 22,where like reference numerals indicate like elements. The operatorsupport assembly 1200 may be incorporated into a truck similar to theone illustrated in FIG. 1 or other materials handling vehicles. Theoperator support assembly 1200 is constructed in substantially the samemanner as operator support assembly 900 illustrated in FIGS. 12-17, but,in addition, a backrest assembly 1210 is provided. The backrest assembly1210 comprises a support 1212 and a pad 1214 coupled to the support1212. The support 1212 is fixedly coupled to the main body 936 of thecarriage assembly 934 so as to move with the carriage assembly 934.Hence, as the carriage assembly 934 moves upward and downward as a truckin which the assembly 1200 is incorporated encounters bumps and holes,the backrest assembly 1210 moves with the floorboard (not shown in FIG.22) coupled to the carriage assembly 934 and the operator. It is alsocontemplated that an armrest, a control knob or lever such as amultifunction controller or steering tiller or other elements typicallyfound within an operator's compartment may be fixedly coupled to thecarriage assembly 934 so that they move with the carriage assembly 934and the floorboard.

Many alterations and modifications may be made by those having ordinaryskill in the art without departing from the spirit and scope of theinvention. Therefore, it must be understood that the illustratedembodiments have been set forth only for the purposes of example andthat they should not be taken as limiting the invention as defined bythe following claims. For example, the mast assembly 130 may comprisetwo or more channels 132A fixedly coupled to the frame 14 of the truckmain body 12, and two or more corresponding carriage assemblies 134Acapable of vertical movement within the channels 132A.

The definitions of the words or elements of the following claims shallinclude not only the combination of elements which are literally setforth, but all equivalent structure, material or acts for performingsubstantially the same function in substantially the same way to obtainsubstantially the same result. In this sense it is thereforecontemplated that an equivalent substitution of two or more elements maybe made for any one of the elements in the claims below or that a singleelement may be substituted for two or more elements in a claim.

Insubstantial changes from the claimed subject matter as viewed by aperson with ordinary skill in the art, now known or later devised, areexpressly contemplated as being equivalently within the scope of theclaims.

The claims are thus to be understood to include what is specificallyillustrated and described above, what is conceptually equivalent, whatcan be obviously substituted and also what essentially incorporates theessential idea of the invention.

1. A materials handling vehicle comprising: a frame; a set of wheelssupported on said frame to allow said materials handling vehicle to moveacross a floor surface; and an operator support assembly comprising asuspended floorboard upon which an operator may stand and an energyabsorbing structure coupled to said frame and said suspended floorboardfor absorbing and dissipating at least a portion of energy resultingfrom disturbances encountered by the vehicle as it moves across thefloor surface prior to said energy portion reaching the operatorstanding on said suspended floorboard, said energy absorbing structureincluding a damping element for effecting a damping function.
 2. Amaterials handling vehicle as set forth in claim 1, wherein said dampingelement comprises at least one damper.
 3. A materials handling vehicleas set forth in claim 2, wherein said energy absorbing structure furthercomprises at least one spring for receiving and storing energy.
 4. Amaterials handling vehicle as set forth in claim 3, wherein said energyabsorbing structure further comprises a mast assembly coupled to saidframe and said floorboard for permitting movement of said suspendedfloorboard relative to said frame.
 5. A materials handling vehicle asset forth in claim 4, wherein said energy absorbing structure furthercomprises structure coupled between said frame and said at least onespring for varying a preload on said at least one spring.
 6. A materialshandling vehicle as set forth in claim 5, wherein said structure coupledbetween said frame and said at least one spring for varying a preload onsaid at least one spring comprises a motor provided with a screw.
 7. Amaterials handling vehicle as set forth in claim 5, wherein saidstructure coupled between said frame and said at least one spring forvarying a preload on said at least one spring comprises a lever capableof being manually moved by an operator.
 8. A materials handling vehicleas set forth in claim 4, wherein said energy absorbing structure furthercomprises: a first member pivotable about a first pivot point coupled tosaid frame, said floorboard being supported by said first member; asecond member pivotable about a second pivot point coupled to said frameand spaced from said first pivot point; and said at least one springextending between and being coupled to said first and second members andsaid at least one damper engaging said first member, said second memberbeing adjustable about said second pivot point so as to adjust a preloadon said at least one spring.
 9. A materials handling vehicle as setforth in claim 3, wherein said energy absorbing structure furthercomprises a scissors mechanism positioned between said floorboard and abase of said frame.
 10. A materials handling vehicle as set forth inclaim 9, wherein said scissors mechanism comprises: a pair of first andsecond scissor arms, said first scissor arm being pivotably coupled at afirst end to said base of said frame and having a second end inengagement with said floorboard, and said second scissor arm beingpivotably coupled at a first end to said floorboard and having a secondend in engagement with said base of said frame; and a pair of third andfourth scissor arms, said third scissor arm being pivotably coupled at afirst end to said base of said frame and having a second end inengagement with said floorboard, and said fourth scissor arm beingpivotably coupled at a first end to said floorboard and having a secondend in engagement with said base of said frame.
 11. A materials handlingvehicle as set forth in claim 9, wherein said at least one spring isgenerally vertically positioned and coupled between said frame and saidscissors mechanism, and said at least one damper is generally verticallypositioned and coupled between said frame and said scissors mechanism.12. A materials handling vehicle as set forth in claim 9, wherein saidat least one spring is generally horizontally positioned and coupledbetween said frame and said scissors mechanism, and said at least onedamper is generally horizontally positioned and coupled between saidframe and said scissors mechanism.
 13. A materials handling vehicle asset forth in claim 9, wherein said energy absorbing structure furthercomprises: a first member pivotable about a first pivot point coupled tosaid frame, said floorboard being supported by said first member; asecond member pivotable about a second pivot point coupled to said frameand spaced from said first pivot point; and said at least one springextending between and being coupled to said first and second members andsaid at least one damper engaging said first member, said second memberbeing adjustable about said second pivot point so as to adjust a preloadon said at least one spring.
 14. A materials handling vehicle as setforth in claim 1, wherein said damping element comprises a valve.
 15. Amaterials handling vehicle as set forth in claim 14, wherein said energyabsorbing structure further comprises: a hydraulic piston/cylinder unitcoupled to said frame; and a ride accumulator capable of receiving andstoring energy, said valve being positioned between said piston/cylinderunit and said ride accumulator.
 16. A materials handling vehicle as setforth in claim 15, wherein said energy absorbing structure furthercomprises a mast assembly coupled to said hydraulic piston/cylinderunit, said frame and said floorboard for permitting movement of saidsuspended floorboard relative to said frame.
 17. A materials handlingvehicle as set forth in claim 15, wherein said valve comprises a needlevalve.
 18. A materials handling vehicle as set forth in claim 17,further comprising a processor-controlled valve capable of allowingpressurized fluid to pass to said hydraulic piston/cylinder unit andsaid ride accumulator.
 19. A materials handling vehicle as set forth inclaim 15, wherein said valve comprises a first processor-controlledvalve.
 20. A materials handling vehicle as set forth in claim 19,wherein said an energy absorbing structure further comprises: a secondprocessor-controlled valve, a height adjust accumulator, a thirdprocessor-controlled valve and a processor for controlling said first,second and third valves.
 21. A materials handling vehicle as set forthin claim 20, wherein said processor causes said first valve to be in afirst position such that said first valve is closed when an operatorenters or exits a rider compartment in which said operator assembly islocated and moves said first valve to a second position when the vehicleis in motion so as to open said first valve to allow said floorboard tomove relative to said frame.
 22. A materials handling vehicle as setforth in claim 21, wherein said processor effects a floorboard heightadjustment operation when said floorboard is spaced from a neutralposition after an operator has stepped onto said floorboard and saidfirst valve has been moved to said second position.
 23. A materialshandling vehicle as set forth in claim 22, wherein said processor movessaid second valve to a closed state when a floorboard height adjustmentoperation is not being effected.
 24. A materials handling vehicle as setforth in claim 23, wherein said processor moves said second valve to anopen state so as to allow pressurized air within said ride accumulatorto be released when said floorboard is to be lowered to said neutralposition during a floorboard height adjustment operation.
 25. Amaterials handling vehicle as set forth in claim 24, wherein saidprocessor moves said third valve to a second position to allowpressurized fluid to enter said height adjust accumulator andsubsequently moves said second valve to its open state when saidfloorboard is to be raised to said neutral position during a floorboardheight adjustment operation.
 26. A materials handling vehicle as setforth in claim 1, wherein said energy absorbing structure furthercomprises a mast assembly coupled to said frame and said floorboard forpermitting movement of said suspended floorboard relative to said frameand structure for releasably locking said floorboard to said frame whenan operator enters or exits a rider compartment in which said operatorassembly is located.
 27. A materials handling vehicle as set forth inclaim 1, wherein said operator support assembly further comprises abackrest assembly coupled to said suspended floorboard so as to movewith said suspended floorboard.
 28. A materials handling vehicle as setforth in claim 1, wherein said damping element comprises at least onedamper at least partially filled with a liquid.
 29. A materials handlingvehicle as set forth in claim 28, wherein said energy absorbingstructure further comprises at least one spring for receiving andstoring energy.